ARTICLE | doi:10.20944/preprints202105.0332.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: kefir; alfalfa; silage; fermentation quality; microbial communities
Online: 14 May 2021 (13:13:37 CEST)
The present study has been one of the first attempts to thoroughly examine the effects of different kefir sources on fermentation characteristics, aerobic stability, and microbial communities of alfalfa silages. The effects of commercial kefir (CK) and homemade kefir culture (HK) applied with four different application doses (untreated control (CON), 5.0, 5.7, and 6.0 log cfu g-1) on wilted alfalfa and stored at an ambient temperature of 25-30 °C. After 45 days ensiling, fermentation characteristics and aerobic stability of silages were measured and bacterial diversity was investigated by 16S ribosomal RNA gene sequencing using GenomeLab™ GeXP platform. Both CK and HK accelerate more lactic acid production and reduced ammonia nitrogen concentration. Factor analysis of kefir sources suggest that the addition of kefir improves the aerobic stability of silages even the initial water soluble carbohydrate (WSC) content is inadequate via its antimicrobial effect on yeast and mould formation. Enterococcus faecium, Pediococcus pentosaceous, and Lactobacillus brevis were dominant bacterial species among the treated groups at silo opening while Lactobacillus plantarum and Lactobacillus brevis became dominant bacterial species after 7 days of aerobic exposure. In conclusion, application of kefir on alfalfa silages improves fermentation quality and aerobic stability even with low WSC content.
ARTICLE | doi:10.20944/preprints202302.0246.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: Cigar; stacking fermentation; microbial community; volatiles; interaction; aroma
Online: 15 February 2023 (01:49:13 CET)
Cigar stacking fermentation is a key step in tobacco aroma enhancement and miscellaneous gas reduction, which both have a great influence on increasing cigar flavor and improving industrial availability. To analyze the effect of cigar tobacco leaf (CTLs) microbial community structure on volatiles during cigar stacking fermentation, this study used multi-omics technology to reveal the changes in microbial community structure and volatiles of different cigar varieties during stacking fermentation, in addition to exploring the interaction mechanism of microbiome and volatiles. The results showed that the dominant microbial compositions of different CTL varieties during stacking fermentation were similar, which included Staphylococcus, Corynebacterium 1, Aerococcus, and Aspergillus. These dominant microbes mainly affected the microbial community structure and characteristic microorganisms of CTLs through microbial interactions, thereby influencing the transformation of volatiles. Characteristic microorganisms of different CTLs varieties such as Trichothecium, Trichosporon, Thioalkalicoccus and Jeotgalicoccus, were found to posively correlate with characteristic volatiles like megastigmatrienone 4, pyrazine, tetramethyl-, geranyl acetone, and 2-undecanone, 6,10-dimethyl-, respectively. This in turn affected the aroma and sensory quality of the CTLs. This study provides theoretical support for the analysis of the mechanism of microorganisms on volatiles and aroma, and development of microbial agents during cigar stacking fermentation.
ARTICLE | doi:10.20944/preprints202108.0280.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: Pozol; lactic acid bacteria; fermentation; starch; microbial dynamics
Online: 12 August 2021 (15:50:05 CEST)
Pozol is a Mexican beverage prepared from fermented nixtamalized maize dough. To contribute to understanding its complex microbial ecology, the effect of inoculating on MRS-starch pure and mixed cultures of amylolytic Sii-25124 and non-amylolytic W. confusa 17, isolated from pozol, were studied on their interactions and fermentation parameters. These were compared with L. plantarum A6, an amylolytic strain isolated from cassava. Microbial growth, kinetic parameters, amylolytic activity, lactic acid production, and hydrolysis products from starch fermentation were measured. The population dynamics were followed by qPCR. L. plantarum A6 showed higher enzymatic activity, lactic acid, biomass production, and kinetic parameters than pozol LAB in pure cultures. Mixed culture of each pozol LAB with L. plantarum A6 showed a significant decrease in amylolytic activity, lactic acid yield, specific growth rate, and specific rate of amylase production. The interaction between Sii-25124 and W. confusa 17 increased the global maximum specific growth rate (µ), the lactic acid yield from starch (Ylac/s), lactic acid yield from biomass (Ylac/x), and specific rate of lactic acid production (qlac) by 15, 30, 30, and 40%, respectively compared with the pure culture of Sii-25124. Interactions between the two strains are essential for this fermentation.
ARTICLE | doi:10.20944/preprints201809.0014.v1
Subject: Engineering, Energy And Fuel Technology Keywords: electrodialysis; bioelectrochemical system; microbial fuel cell; C1 gas; carbon monoxide; acetate
Online: 3 September 2018 (08:06:49 CEST)
The conversion of C1 gas feedstock, such as carbon monoxide (CO), into useful platform chemicals has attracted considerable interest in industrial biotechnology. One conversion method is electrode-based electron transfer to microorganisms using bioelectrochemical systems (BESs). In this BES system, acetate is the predominant component of various volatile fatty acids (VFAs). To appropriately separate and concentrate the produced acetate, a BES type electrodialysis cell with an anion exchange membrane was constructed and evaluated under various operational conditions, such as the applied external current. The higher acetate flux of 23.9 mmol/m2∙hr was observed under -15 mA current in an electrodialysis-based bioelectrochemical system. In addition, the initial acetate concentration affects the separation efficiency and transportation rate. The maximum flux appeared at 48.6 mmol/m2∙hr when the acetate concentration was 100mM, whereas the effect of the initial pH of the anolyte was negligible. The acetate flux was 14.9 mmol/m2∙hr when actual fermentation broth from BES based CO fermentation, was used as a catholyte. A comparison of the synthetic medium with the actual fermentation medium suggests that unknown substances and metabolites in the actual medium interfere with electrodialysis in the BES. These results provide information on the separation and optimal concentration for VFAs produced by C1 gas fermentation through electrodialysis, and a combination of a BES and electrodialysis.
ARTICLE | doi:10.20944/preprints202307.1548.v1
Subject: Biology And Life Sciences, Animal Science, Veterinary Science And Zoology Keywords: methane; ammonia; Leucaena leucocephala; Pricky pear; microbial population; in vitro fermentation
Online: 25 July 2023 (10:10:29 CEST)
In this study, four experimental treatments were evaluated: (T1) alfalfa hay + concentrate, (50:50%, DM); (T2) alfalfa hay + Leucaena leucocephala + concentrate, (30:20:50%, DM); (T3) alfalfa hay + prickly pear + concentrate, (30:20:50%, DM); and (T4) alfalfa hay + Leucaena leucocephala + prickly pear + concentrate, (30:10:10:50%, DM). NH3-N concentrations in T2 and T4 decreased when replaced alfalfa hay in 20 and 10 %, respectively. Treatments did not affect the concentration of total volatile fatty acids (TVFA) between T3 and T4 (p>0.05); while the concentrations among T1 and T2 were different (P<0.05). T2 showed a reduction of 25.5 % in the methane production when compared to T1(p < 0.05).The lowest concentrations of protozoa were observed in T2 and T4, which contained Leucaena leucocephala (T2) and Leucaena leucocephala + prickly pear (T4) (p<0.05). The highest concentration of total methanogens was recorded in T1 and were different to T2, T3 and T4 (p<0.05). Leucaena leucocephala at a inclusion percentage of 20 % decreased the methane when compared to T1; whereas prickly pear there was not a positive effect the methane production.
ARTICLE | doi:10.20944/preprints202307.0954.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: Cocoa Bean Fermentation; Yeast; Lactic Acid Bacteria; Acetic Acid Bacteria; Initiator Microbial Consortium
Online: 14 July 2023 (11:12:17 CEST)
Fine aroma cocoa (Theobroma cacao) is one of Ecuador's most iconic export products, representing 63% of world production; however, few advances have been made in fermentation processes that greatly influence the development of chocolate´s organoleptic characteristics. The study of starter cultures has been investigated in other countries, which seek to improve organoleptic properties or decrease fermentation time. The aim of this study was to analyze the effect of a native microbial consortium based on two yeasts (Torulaspora delbrueckii and Hanseniaspora uvarum), a lactic acid bacterium (LAB) (Lactobacillus plantarum) and an acetic acid bacterium (AAB) (Acetobacter ghanensis) inoculated at the beginning of the fermentative process, on physical and biochemical variables, microbial population dynamics, and percentage of almond fermentation. The started culture caused changes in sugar and acid content, which in turn generated temperature and pH changes in the dough, resulting in the dynamics of yeast, AAB, and mesophilic microorganisms remaining higher than those of the control throughout the fermentation process; a decrease of filamentous fungi that affect the flavor and quality of beans due to the production of acetic acid or secondary metabolites from yeasts and LAB; and optimized fermentation percentage by 24% higher than spontaneous fermentation in only 96 hours.
ARTICLE | doi:10.20944/preprints202309.2058.v1
Subject: Biology And Life Sciences, Animal Science, Veterinary Science And Zoology Keywords: Caragana korshinskii Kom.; flavonoids; Taraxacum mongolicum Hand.-Mazz.; fermentation quality; antioxidant status; microbial community
Online: 29 September 2023 (04:26:21 CEST)
The present study was to investigate effects of total flavonoids from Taraxacum mongolicum Hand.-Mazz. (FT) on fermentation quality, antioxidant status and microbial community of Caragana korshinskii Kom. (CK) silage. CK was ensiled with no additive (CON), 1% FT and 2% FT on a fresh weight (FW) basis for 60 days. The results showed that 1% FT and 2% FT groups displayed higher DM content than CON group, and 2% FT group had the best effect on nutrient preservation. Compared with CON and 1% FT groups, 2% FT group exhibited the best silage fermentation quality and the highest antioxidant activity, including increased lactic acid, acetic acid concentrations and the activities of antioxidant enzymes, as well as decreased pH and the ammonia nitrogen (NH3-N) concentration. Moreover, 2% FT addition significantly affected the microbial community, such as increased abundance of Lactobacillus and decreased abundances of Pseudomonas and unidentified Cyanobacteria. The abundances of Lactobacillus parafarraginis and Lactobacillus brevis were negatively correlated to pH, while they were positively correlated with T-AOC, GSH-Px and CAT activities. In conclusion, 2% FT may be used as additives to inhibit the growth of undesirable microorganisms and promote fermentation quality and antioxidant activity of CK silage.
REVIEW | doi:10.20944/preprints202307.1625.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: Microbial biofertilizers; microbial symbioses; plant interactions; crop resistance
Online: 25 July 2023 (08:58:55 CEST)
To identify soil microbial communities, it is essential to understand their phenotypic and genetic characteristics. Plant growth-promoting rhizobacteria (PGPR) are bacteria capable of promoting plant growth. In addition, rhizobacteria also serve as biological control agents. In addition to fixing atmospheric nitrogen, solubilising insoluble phosphate and secreting hormones such as indoloacetic acid, kinetics and gibberellins, plant growth-promoting rhizobacteria help plants grow directly. Furthermore, they facilitate plant growth indirectly by inducing systemic resistance, siderophores, antibiotics, lytic enzymes, hydrogen cyanide production and stress regulation. This review examines in detail the direct and indirect mechanisms of PGPR action and their interaction in plant growth and resistance.
ARTICLE | doi:10.20944/preprints202304.0851.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: Herbicides; mixed toxicity; microbial diversity; microbial community structure
Online: 24 April 2023 (10:49:58 CEST)
As two commonly-used non-selective herbicides, glyphosate (GP) and diquat (DQ) are easily co-resided in lateritic paddy soil due to the rich iron/aluminum oxides, nevertheless there is limited information on their co-impact on microbial diversity and community structure in this type soil. In this study, the short-term effects of combined GP and DQ on soil microbial diversity and community structure shifts were investigated in lateritic paddy soil from a tropical agricultural region (Hainan, China) based on 16S rRNA and ITS high-throughput sequencing technology. The results showed that mixed herbicides promoted the abundance of Streptomyces in bacteria (0.45-1.84%) and Curvularia in fungi (0.01-5.85%), while GP and DQ had inhibitory effects on the abundance of Streptomyces (0.13-2.21%) and Curvularia (0.03-1.13%), which were significantly different with their single exposure (p < 0.05); the combined application of the two herbicides aggravate the adverse effect on the diversity of soil fungal community (p < 0.05), although their mixture did not have a greater impact on the soil bacteria abundance/diversity and fungi abundance (p > 0.05). Results suggested that the combined application of GP and DQ affected the fungal diversity although they did not cause other significant negative effects on soil microorganisms, hinting that more attention should be paid to the mixed effect caused by GP and DQ on specific fungal populations in lateritic paddy soil.
ARTICLE | doi:10.20944/preprints202308.0358.v1
Subject: Engineering, Civil Engineering Keywords: microplastics; activated sludge; nutrient removal; microbial activity; microbial community
Online: 4 August 2023 (14:43:30 CEST)
A large number of microplastics (MPs) have been found in various stages of wastewater treatment plants, which may affect the functional microbial activity in activated sludge and lead to unstable pollutant removal performance. In this study, the effects of different concentrations of polylactic acid microplastics (PLA MPs) on system performance, nitrification and phosphorus (P) removal activities, and extracellular polymeric substances (EPS) were evaluated. The results showed that under the same influent conditions, low concentrations (50 particles/(g TS)) of PLA MPs had no significant effect on effluent quality. The average removal efficiencies of chemical oxygen demand, phosphate and ammonia were all above 80%, and the average removal efficiencies of total nitrogen remained above 70%. High concentrations (200 particles/(g TS)) of PLA MPs inhibited the activities of polyphosphate accumulating organisms (PAOs) and nitrifying bacteria. The specific anaerobic P release rate decreased from 37.7 to 23.1 mg P/(g VSS·h), and the specific aerobic P uptake rate also decreased significantly. The specific ammonia oxidation rate decreased from 0.67 to 0.34 mg N/(g VSS·h), while the change in specific nitrite oxidation rate was not significant. The dosing of PLA MPs decreased the total EPS and humic acid content. As the concentration of PLA MPs increased, microbial community diversity increased. The relative abundance of potential PAOs (i.e., Acinetobacter) increased from 0.08% to 12.57%, while the relative abundance of glycogen accumulating organisms (i.e., Competibacter and Defluviicoccus) showed no significant changes, which would lead to improved P removal performance. The relative abundance of denitrifying bacteria (i.e., Pseudomonas) decreased from 95.43% to 58.98%, potentially contributing to the decline in denitrification performance.
REVIEW | doi:10.20944/preprints202306.0299.v1
Subject: Environmental And Earth Sciences, Other Keywords: anaerobic digestion; microbial structure; microbial interactions; operating parameters; digestion efficiency
Online: 5 June 2023 (10:09:58 CEST)
Anaerobic digestion has emerged as an increasingly popular method for the effective management of organic waste and wastewater with the potential to generate renewable energy. However, efficient digestion depends heavily on the complex and diverse microbial communities mediating this process. This review paper delves into the complex microbiome that exists within anaerobic digestion digesters, playing a critical role in the efficient and sustainable conversion of organic waste into biogas. Its primary focus falls within the scope of how various operational and environmental factors, including temperature, pH, hydraulic retention time, substrate loading rates, and the presence of inhibitory compounds, can substantially impact the microbiome of these systems. Through an extensive analysis of the existing literature, the microbial ecology of anaerobic digestion, including the composition and function of the microbial community, their interactions, and responses to different stressors, are evaluated. By offering critical insights into the distribution patterns of active microbial populations upon alterations in various process parameters, a better understanding of the microbial dynamics within these systems is provided, enhancing their efficiency. Overall, this paper emphasizes the importance of unraveling the microbial evolution within AD reactors to optimize biogas production and sustainable waste management and proposes future perspectives in this direction.
DATA DESCRIPTOR | doi:10.20944/preprints202106.0368.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Microbial Mash database, Mash distance, Genome containment, Type material, Microbial taxonomy
Online: 14 June 2021 (14:54:32 CEST)
The analysis of curated genomic, metagenomic, and proteomic data are of paramount importance in the fields of biology, medicine, education, and bioinformatics. Although this type of data is usually hosted in raw form in free international repositories, its access requires plenty of computing, storage, and processing capacities for the domestic user. The purpose of the study is to offer a comprehensive set of genomic and proteomic reference data, in an accessible and easy-to-use form to the scientific community. A representative type material set of genomes, proteomes and metagenomes were directly downloaded from the site: https://www.ncbi.nlm.nih.gov/assembly/ and from Genome Taxonomy Database, associated with the major groups of Bacteria, Archaea, Virus, and Fungi. Sketched databases were subsequently created and stored on handy raw reduced representations, by using Mash software. Our dataset contains near to 100 GB of space disk reduced to 585.78 MB and represents 87,476 genomics/proteomic records from eight informative contexts, which have been prefiltered to make them accessible, usable, and user-friendly with computational resources. Potential uses of this dataset include but are not limited to, microbial species delimitation, estimation of genomic distances, genomic novelties, paired comparisons between proteomes, genomes, and metagenomes.
REVIEW | doi:10.20944/preprints202307.1686.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: Microbial biofertilizers; microbial symbioses; plant interactions; crop resistance; plant stimulation; sustainable agriculture
Online: 26 July 2023 (02:47:09 CEST)
In sustainable agriculture, plant nutrients are the most important elements. Biofertilizers introduce microorganisms that improve the soil nutrients and increase their accessibility to crops. In order to meet the demands of a growing population, healthy crops need to be produced using the right type of fertilizers to provide them with all the major nutrients they require. However, an increasing dependency on chemical fertilizers is destroying the environment and negatively af-fecting the health of humans. Thus, using microbes as bioinoculants as the best replacement of chemical fertilizers as eco-friendly way for plant growth and soil fertility is believed to be the best method for improving plant growth and soil fertility. In sustainable agriculture, these microbes provide significant benefits to crops. In addition to colonizing plant systems (epiphytic, endo-phytic, and rhizospheric), beneficial microbes play a key role in absorbing nutrients from surrounding ecosystems. Plant associate microbes can promote plant growth regardless of natural and extreme conditions. Plant growth promoting microbes promote plant growth through a variety of direct and indirect methods, such as nitrogen fixation, plant growth hormone production, siderophores, HCN, several hydrolytic enzymes, and potassium, zinc, and phosphorus solubilization. Research on biofertilizers has been extensive and even available, which demonstrates how these microbes can deliver nutrients to crops in sufficient quantities to enhance their yield. This review examines in detail the direct and indirect mechanisms of PGPR action and their interaction in plant growth and resistance.
ARTICLE | doi:10.20944/preprints202307.1824.v1
Subject: Environmental And Earth Sciences, Waste Management And Disposal Keywords: wine; electrolysis; microbial cell; optimization.
Online: 27 July 2023 (08:35:16 CEST)
This study aimed to optimize the bioelectricity production process using a vinasse solution through the application of Plackett-Burman and Box-Behnken designs. An electrochemical cell was constructed using Arduino to measure the potential difference between the anode and cathode immersed in the vinasse solution, a byproduct of wine production containing organic compounds and ions that undergo redox reactions. The Plackett-Burman design identified the most influential variables among eight previously selected, including vinasse concentration, agitation, and yeast, which positively affected millivolt production, while temperature showed a negative correlation. Based on these results, the Box-Behnken design was used for process optimization, varying parameters such as concentration, stirring, and sodium chloride. Response surface graphs demonstrated the relationship between these variables and millivolt production. The findings indicate that higher agitation levels, lower concentrations of vinasse, and the addition of sodium chloride can enhance bioelectricity generation. The study provides insights into the bioelectricity production process from vinasse, contributing to the understanding and potential for sustainable energy generation. The methodology involving Arduino-based measurement and the utilization of experimental designs offers a systematic approach to optimize bioelectricity production from vinasse.
CONCEPT PAPER | doi:10.20944/preprints202107.0546.v1
Subject: Biology And Life Sciences, Anatomy And Physiology Keywords: Bacterial nomenclature; taxonomy; microbial genomics
Online: 23 July 2021 (14:22:59 CEST)
The remarkable success of taxonomic discovery, powered by culturomics, genomics and metagenomics, creates a pressing need for new bacterial names, while holding a mirror up to the slow pace of change in bacterial nomenclature. Here, I take a fresh look at bacterial nomenclature, exploring how we might create a system fit for the age of genomics, playing to the strengths of current practice, while minimising difficulties. Adoption of linguistic pragmatism, obeying the rules while treating recommendations as merely optional will make it easier to create names derived from descriptions, from people or places or even arbitrarily. Simpler protologues and a relaxed approach to recommendations will also remove much of the need for expert linguistic quality control. Automated computer-based approaches will allow names to be created en masse before they are needed, while also relieving microbiologists of the need for competence in Latin. The result will be a system that is accessible, inclusive and digital, while also fully capable of naming the unnamed millions of bacteria.
ARTICLE | doi:10.20944/preprints202012.0254.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Microbial quality; frozen chicken meat
Online: 10 December 2020 (12:27:31 CET)
Background: There is an upsurge in the consumption of chicken meat leading to a high influx of imported frozen chicken parts into the Ghanaian markets with little information on their microbial qualities. This study examined the microbial quality of imported frozen chicken parts from three major import countries (USA, the Netherlands and Brazil) into the Kumasi Metropolis. Methods: A total of 45 chicken meat parts of 15 thighs, wings and backs from wholesale cold stores market in the Kumasi Metropolis were randomly sampled for laboratory examinations. A ten-fold serial dilution was performed on each homogenized chicken parts to determine microbiological quality using Plate Count Agar , MacConkey Agar (MCA), Mannitol Salt Agar (MSA) and Desoxycholate Citrate Agar (DCA) for the total viable count (TVC), total coliform count (TCC), Staphylococcus and Salmonella spp counts respectively incubated at 37oC for 48 hours. Sabouraud Dextrose Agar (SDA) was used for fungal counts. We identified bacterial and fungal isolates using appropriate laboratory and biochemical tests. Descriptive data analysis was carried using SPSS-IBM version 16. Results: Mean TVCs of 5.93, 5.98 and 6.14 log10cfu/g were recorded for frozen chicken meats from the USA, the Netherlands and Brazil respectively. Means TCCs of 6.14, 5.93 and 5.98 log10cfu/g were obtained for chicken meats from Brazil, USA and the Netherlands respectively. Staphylococcus spp. (35.4%), E. coli (26.2%), Salmonella spp. (24.6%), and Klebsiella spp. (13.8%) were isolated with Aspergillus spp (33.3%), Rhizopus spp (27.3%), Penicillin spp (24.2%), and Cladosporium spp (15.2%). Chicken thighs, backs and wings recorded 46.2%, 29.2% and 24.6% bacterial contaminants in this order. Bacterial isolates of 49.2%, 28.8% and 22.0% were recorded in frozen chicken meat products from Brazil, the Netherlands USA respectively. Conclusion: The results suggest that imported frozen chicken meats into the Ghanaian market have moderate quality with potential pathogens such as E. coli and Salmonella spp.
ARTICLE | doi:10.20944/preprints202309.0361.v1
Subject: Physical Sciences, Applied Physics Keywords: Microbial fuel cell; Microfluidics; Fluidic separator; Single Chamber Microbial Fuel Cell; Energy Recovery optimization
Online: 6 September 2023 (03:45:37 CEST)
This study proposes a redesign of asymmetric single-chamber microbial fuel cells (a-SCMFC) with the goal of optimizing energy production. The new approach is based on the introduction of an Intermediate Microfluidic Septum (IMS) as a relatively simple and inexpensive method to opti-mize both electrolyte flow and species transfer inside the devices. SCMFCs with the novel IMS, operated with sodium acetate as the carbon source, demonstrate to enhance the energy recovery (Erec) factor, defined as the ratio between the energy yield and the inner volume of electrolyte. In standard operative conditions, cells with IMS exhibit Erec value of (37±1) J/m3, with respect to (3.0±0.3) J/m3 of control cells. Furthermore, changing sodium acetate concentration the Erec values change accordingly. By monitoring the activity of a-SCMFCs for over one-year, beneficial impact of the IMS on both the initial inoculation phase and the long-term stability of electrical perfor-mance were observed. These improvements suggest the effectiveness of IMS to allow the de-velopment of efficient biofilms, likely due to the reduction in oxygen diffusion towards the anode. Electrochemical characterizations confirm that the presence of the IMS impacts the diffusion processes inside the electrolytic chamber, supporting the hypothesis of a beneficial effect on oxygen diffusion.
REVIEW | doi:10.20944/preprints202207.0230.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: intercropping; nitrogen transfer; microbial community structure; microbial activity; DNA-SIP; high-throughput sequencing; metagenomes
Online: 15 July 2022 (09:38:10 CEST)
Intercropping systems can flexibly use resources such as sunlight, heat, water, and nutrients in time and space, improve crop yield and land utilization rates, effectively reduce continuous cropping obstacles and the occurrence of diseases and insect pests, and control the growth of weeds. Thus, intercropping is a safe and efficient ecological planting mode. The legume–cereal intercropping system is the most common planting combination. Legume crops fix nitrogen from the atmosphere through their symbiotic nitrogen fixation abilities, and the fixed nitrogen can be transferred to and utilized by cereal crops in various ways. The symbiotic nitrogen fixation efficiency of legume crops was improved by reducing the inhibition of soil nitrogen on nitrogenase activity through competitive absorption of soil nitrogen. However, the effects of nitrogen transformation and distribution in intercropping systems, and microbial community structure characteristics on nitrogen transfer need to be further explored. In this review, ⅰ) we present the transformation and distribution of nitrogen in the legume–cereal intercropping system; ⅱ) we describe the soil microbial community characteristics in intercropping systems; and ⅲ) we discuss the advantages of using modern biological molecular techniques to study soil microorganisms. We conclude that intercropping can increase the diversity of soil microorganisms, and the interaction between different plants has an important impact on the diversity and composition of the bacterial and fungal communities. The extensive application of modern biological molecular techniques in soil microbial research and the great contribution of intercropping systems to sustainable agriculture are particularly emphasized in this review.
REVIEW | doi:10.20944/preprints202009.0548.v1
Subject: Biology And Life Sciences, Biology And Biotechnology Keywords: genome-scale metabolic model; microbial community; optimization; design; engineering; computational methods; synthetic microbial consortia
Online: 23 September 2020 (09:52:17 CEST)
Microbes do not live in isolation but in microbial communities. The relevance of microbial communities is increasing due to the awareness about their biotechnological influences in a huge number of environmental, health and industrial processes. Hence, being able to control and engineer the output of both natural and synthetic communities would be of great interest. However, most of the available methods and biotechnological applications (both in vivo and in silico) have been developed in the context of isolated microbes. In vivo microbial consortia development, i.e. to reproduce the community life conditions in the wet-lab, is extremely difficult and expensive requiring of computational approaches to advance knowledge about microbial communities, mainly with descriptive modelling, and further with engineering modelling. In this review we provide a detailed compilation of available examples of engineered microbial communities as a launch pad for an exhaustive and historical revision of those computational methods devoted so far toward the better understanding, and rational engineering of natural and synthetic microbial communities.
ARTICLE | doi:10.20944/preprints202203.0353.v1
Subject: Environmental And Earth Sciences, Soil Science Keywords: chlorothalonil; dissipation; enzyme activity; microbial community
Online: 28 March 2022 (03:46:35 CEST)
To get a better knowledge of the effects of residual chlorothalonil on soil characteristics and soil microbial communities, we evaluated the dissipation of chlorothalonil and the effects of different chlorothalonil concentrations on soil respiration, enzyme activities, and microbial community structure in yellow-brown loam soils. Bacterial and fungal soil communities were examined using traditional plate counting and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR–DGGE) methods. Soil properties and the results of DGGE band analysis were both used to estimate the status of the soil microbial ecosystem. The results show that residual chlorothalonil has considerable effects on soil respiration, enzymatic activities, and microbial community structure. In particular, soil respiration and phosphatase activities were increased, while saccharase activity, microbial biomass, and microbial community diversity were decreased by increasing levels of chlorothalonil treatment. Correlation analyses revealed that the application of chlorothalonil was significantly correlated with the change of the soil respiration, urease activity, sucrase activity, soil culturable bacteria and culturable fungi biomass. We conclude that residual chlorothalonil is directly related to soil respiration, enzyme activities, and microbial community structure.
ARTICLE | doi:10.20944/preprints202106.0519.v1
Subject: Biology And Life Sciences, Anatomy And Physiology Keywords: Polyethylene terephthalate; Microbial degradation; Sustainable development
Online: 21 June 2021 (14:52:03 CEST)
Plastics are extensively used due to their versatility, durability, and low cost. PET stands for Polyethylene terephthalate. PET plastic is widely used all over the world and has many applications ranging from water bottles to fabrics like polyester and many things in between. But its unrestrained use in every field is resulting in heaps and piles of non-biodegradable materials causing damage to the environment and causing pollution. The idea being proposed is to degrade the PET plastic biologically using different bacteria. The bacteria used in this process are Ideonella sakaiensis, Acetobacterium woodii, Pelotomaculum and Methanospirillum hungatei. PET plastic is degraded, yielding Terephthalic Acid (TPA) and Ethylene Glycol (EG) by the action of the bacterium I. sakaiensis. Degradation of EG by A. woodii results in the formation of acetate and ethanol. TPA is degraded by the action of the coculture of Pelotomaculum and M. hungatei thereby yielding methane and acetate. All these products formed have significant commercial uses in various industries. The complete process that is to be carried out can help in achieving sustainability by fulfilling various Sustainable Development Goals set by the United Nations.
REVIEW | doi:10.20944/preprints201806.0073.v1
Subject: Biology And Life Sciences, Biology And Biotechnology Keywords: wastewater treatment; microbial fuel cells; bioenergy
Online: 6 June 2018 (05:38:03 CEST)
Microbial Fuel Cells (MFCs) representing a promising technology for the extract of energy and resources through wastewater and it also offer an economic solution to the problem of environment effluent and energy crisis in near future. The advance device is rather appealing, due its potential benefits, its practical application is, however hindered by several drawbacks, such an internally competing microbial reaction, and low power generation. This report is an endeavor to address various design connected to the MFCs application to wastewater treatment, in particular cost effective bioelectricity from waste water are reviewed and discussed with a multidisciplinary approach. The conclusions drawn herein can be of practical interest to all new researchers dealing with effluent wastewater treatment using MFCs.
ARTICLE | doi:10.20944/preprints202007.0677.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: conservation agriculture; compost; soil quality; bio-test; macro- and micronutrients; free-living nematodes; microbial respiration; microbial biomass
Online: 28 July 2020 (10:31:47 CEST)
Reduced nutrient mineralization rates under minimum tillage are usually compensated by mineral fertilizer application. These cannot be applied in organic farming systems, however. We hypothesized that organic minimum tillage based on frequent cover cropping and application of dead mulch will improve soil fertility and can compensate for the potential negative effects of minimum tillage. Two long-term field experiments were set up in 2010 and 2011 comparing plough versus minimum tillage including application of transferred mulch. As second factor, the application of compost versus mineral potassium and phosphorus was compared. In 2019, soils were analyzed for soil pH, organic carbon, macro-, micronutrients, microbial biomass, microbial activity and total nematode abundance. In addition, performance of pea in the same soils was determined under greenhouse conditions. Across both experiments, macronutrients (+52%), micronutrients (+11%), microbial biomass (+51%), microbial activity (+86%), and bacterivorous nematodes (+112%) increased in minimum tillage compared with the plough-based system. In the greenhouse, pea biomass was 45% higher in the soil that had been subjected to minimum tillage compared to the plough. In conclusion, soil fertility can be improved in organic minimum tillage systems by intensive cover cropping and application of dead mulch to levels higher than in a plough-based system.
ARTICLE | doi:10.20944/preprints202311.0122.v1
Subject: Biology And Life Sciences, Animal Science, Veterinary Science And Zoology Keywords: Direct-fed microbial; milk yield; dairy cows
Online: 2 November 2023 (04:12:24 CET)
This 16-month study aimed to evaluate the extended effects of administering direct-fed microbials (DFM) on milk yield and components in 150 dairy cows. The cows were randomly divided into two groups: control (n=75) and DFM (n=75) based on parity and days in milk. Throughout the study, the two groups of cows were housed separately in a free stall yard, and each group had their own feeding area. The DFM group received 10 ml/cow of the Lacticaseibacillus- and Lentilactobacillus-based DFM via top dressing of the feed during lactation and drying off. Milk yield and liveweight were recorded daily. Milk samples were collected every two months for milk components analysis. Both groups produced less milk in the second production season due to adverse weather conditions. DFM cows gained more liveweight across the study (19.40 kg, 95% CI 0.44; 38.30) compared to controls. In the second season, DFM cows lost weight at a slower rate (-6.06, 95% CI -10.49; -1.61) during the postpartum period and produced more milk (0.39 L/d 95% CI 0.10; 0.89). Over a full lactation, DFM cows yielded at least 258L (95% CI 252L; 265L) more milk than controls. No significant differences were found in fat yield, protein yield, or somatic cell counts. The study suggests that prolonged DFM administration positively impacted milk production, but further research is needed to understand the underlying mechanism.
REVIEW | doi:10.20944/preprints202310.0689.v1
Subject: Environmental And Earth Sciences, Water Science And Technology Keywords: constructed wetlands; biochar; enzyme activities; microbial communities
Online: 11 October 2023 (07:32:26 CEST)
Constructed wetlands (CWs) is a kind of green environmental protection technology, which is widely used in sewage treatment. The traditional CWs is faced with the problem of low treatment effect of high concentration sewage. In recent years, biochar, as a new type of adsorption material, has been used in CWs because of its advantages of large specific surface area, strong adsorption capacity and wide material sources. This paper systematically summarized the characteristics of biochar and the preparation of biochar by studying the changes of microorganisms added to CWs, and compared the effects of different treatment methods coupled with biochar on the treatment performance of CWs, the effects of biochar coupled with CWs on enzyme activity, functional genes, metabolites and microbial communities were investigated. This review summarizes how different preparation methods affect the properties of biochar and how these biochar cause changes in the microorganisms added to CWs.
ARTICLE | doi:10.20944/preprints202309.0026.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: seagrass, microbial loop, viral lysis, mortality rates
Online: 1 September 2023 (13:02:51 CEST)
In coastal areas around the world, seagrass meadows play a crucial ecological and economic role. A large amount of seagrass beds dominates primary production and contributes to the high secondary productivity of this ecosystem. The microbial loop (consuming bacterial biomass by grazers and using seagrass-derived detritus by bacteria) may be an important mechanism for transferring seagrass-derived organic matter to the aquatic food chain. This study aims to improve our understanding of how bacterial growth and mortality (grazing and viral lysis rates) differ in seagrass and adjacent unvegetated meadow habitats. We found that viral lysis and grazing caused similar mortality rates of bacteria in a seagrass environment during the summer. It has been found, however, that bacterial production is controlled by the availability of resources (bottom-up control) and is cycled within the bacteria-virus-DOC loop in adjacent unvegetated waters. Our study region may be affected by this shift in organic matter fate and cycling.
ARTICLE | doi:10.20944/preprints202308.0478.v1
Subject: Biology And Life Sciences, Food Science And Technology Keywords: Aged vinegar; Microbial community; Physicochemical characteristics; Correlation
Online: 7 August 2023 (04:59:59 CEST)
In this paper, the main physicochemical characteristics and evolutionary laws of microbial community structure during the fermentation of aged vinegar were discussed, and the correlation between Cuqu and microorganisms and physicochemical characteristics during fermentation was explored. The results showed that there are significant differences in genera at different stages of fermentation, the main dominant bacteria in R1 are Bacillus, Lactobacillus, Aspergillus and Issatchenkia. At R2 fermentation stage, Lactobacillus, Acetobacter and Saccharomyces showed an upward trend and finally became absolute advantage bacteria. The main genus of bacteria at the end of overall fermentation is Aspergillus. Correlation analysis shows that in Cuqu, the bacterial genera that are significantly positively and negatively correlated with reducing sugars and amino acid nitrogen are the same, while the bacterial genera that are significantly positively and negatively correlated with pH and saccharification power are the same. During the fermentation process, pH, reducing sugar and saccharification ability are mainly positively correlated with bacterial genera. And research has found that during the fermentation process, the overall correlation between fungal communities and physicochemical characteristics is weaker compared to bacteria.
ARTICLE | doi:10.20944/preprints202306.0669.v1
Subject: Environmental And Earth Sciences, Soil Science Keywords: respirometry; cover crops; conservation systems; microbial biomass
Online: 9 June 2023 (04:44:20 CEST)
Soil quality is a factor which is directly related to the sustainability of agricultural production and can be compromised through the use of inadequate management practices. In this work, soil edaphic respiration and changes in microbial biomass promoted by cover crops in an integrated crop-livestock system (ICLS) were evaluated using soil quality indicators by the respirometry method. The design used was completely randomized in a 3x6 factorial scheme and multivariate principal components analysis (PCA) was performed according to MANOVA. The edaphic respiration was determined based on the respirometry technique. From the results, it was found that edaphic soil respiration was significant in the nine evaluation periods, demonstrating the importance of grass cover on this edaphic respiration arising from the biological activity of microorganisms, which is directly related to the amount of organic carbon in the soil. It was concluded that the use of cover crops contributed to producing organic matter in the soil and consequently greater microbial respiratory activity.
ARTICLE | doi:10.20944/preprints202306.0217.v1
Subject: Biology And Life Sciences, Ecology, Evolution, Behavior And Systematics Keywords: Aquatic microbiology; Bacteria; Microbial ecology; Phytopathogens; Irrigation
Online: 2 June 2023 (15:38:59 CEST)
There is significant lack of information on the presence of plant pathogens in aquifer, increasingly used for irrigation during last decades and considered mostly free of them. In this work, we report the presence of bacteria from the Pseudomonas syringae complex (referred as PsyC) including phytopathogenic bacteria, in groundwater of Avignon, France. Their concentration was variable and inversely correlated with water electrical conductivity. Their mean abundance were hundred times lower than in the river Durance, connected with the aquifer but surprisingly, their genetic structure were more homogeneous. Moreover, most strains (97 %) from groundwater were tested as potentially pathogenic on plants, when in the river they were only 71 %. Determinants of this low diversity and high aggressiveness remain to be identified. We conclude that aquifers must be considered potential plant pathogenic reservoirs even if more surveys are needed to understand the real impact on crops during irrigation. These results could be included in prediction models and new approaches to disease forecasting and surveillance and could lead to adaptation of agricultural practices.
REVIEW | doi:10.20944/preprints202301.0223.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: Microalga; Chlamydomonas; Biotic interactions; Algal-microbial Consortia
Online: 12 January 2023 (09:35:58 CET)
The stability and harmony of ecological niches rely on intricated interactions between their members. During evolution, organisms have developed the ability to thrive in different environments taking advantage of each other’s metabolic symphonies. Among them, microalgae are a highly diverse and widely distributed group of major primary producers whose interactions with other organisms play essential roles in their habitats. Understanding the basis of these interactions is crucial to control and exploit these communities for ecological and biotechnological applications. The green microalga Chlamydomonas reinhardtii, a well-established model, is emerging as a model organism for studying a wide variety of microbial interactions with ecological and economic significance. In this review, we bring together and discuss current knowledge that points to C. reinhardtii as a model organism for studying microbial interactions.
REVIEW | doi:10.20944/preprints201912.0245.v1
Subject: Biology And Life Sciences, Biophysics Keywords: energy; entropy; anabolism; catabolism; microbial cultures; biotechnology
Online: 19 December 2019 (07:00:02 CET)
To understand microbial growth with mathematical models has a long tradition that dates back to the pioneering work of Jacques Monod in the 1940s. Growth laws are simple mathematical expressions that aim at describing growth rates of microbes as functions of external parameters, in particular nutrient concentrations. These laws are now widely applied to construct, e.g., dynamic ecosystem models. However, to explain the growth laws from underlying (first) principles is extremely challenging. In the second half of the 20th century, numerous experimental approaches aimed at precisely measuring heat production during microbial growth to determine the entropy balance in a growing cell and to quantify the exported entropy. This has led to the development of thermodynamic theories of microbial growth, which have generated fundamental understanding and identified principle limitations of the growth process. Whereas these approaches considered a growing microbe as a black box, modern theories heavily rely on genomic resources to describe and model genome-scale networks to explain microbial growth. Interestingly, however, thermodynamic constraints are often included in modern modelling approaches only in a rather superficial fashion, and it appears that recent modelling approaches and classical theories are disconnected fields. In order to stimulate a closer interaction between these fields, we here review various theoretical approaches that aim at describing microbial growth based on thermodynamic principles. We start with classical black-box models of cellular growth, and continue with genome-scale modelling approaches that include thermodynamics, before we place these models in the context of fundamental considerations based on non-equilibrium statistical mechanics. We conclude by identifying conceptual overlaps between the fields and suggest how the various types of theories and models can be integrated. We outline how concepts from one approach may help to inform or constrain another, and we demonstrate how genome-scale models can be used to infer classical black-box parameters, which are experimentally accessible in growth experiments. Such integration will allow understanding to what extent microbes can be viewed as thermodynamic machines, and how close they operate to theoretical optima.
ARTICLE | doi:10.20944/preprints201907.0222.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: antimicrobial resistance; biocuration; microbial nomenclature; molecular epidemiology
Online: 19 July 2019 (08:23:38 CEST)
With the increasing use of genome sequencing as a surveillance tool for molecular epidemiology of antimicrobial resistance, we are seeing an increased intersection of genomics, microbiology, and clinical epidemiology. Clear nomenclature for AMR gene families and pathogens is critical for communication. For CARD release version 3.0.3 (July 2019), we updated the entire CARD database to reflect the latest pathogen names. In total, we detected 48 name changes or updates, some of which reflect major changes in familiar names.
ARTICLE | doi:10.20944/preprints201811.0041.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: Crop rotation; Fertilization; Maize; Microbial community structure
Online: 2 November 2018 (09:37:31 CET)
Examining the soil microbiome structure has a great significance in exploring the mechanism behind plant growth changes due to maize (Zea mays L.) and soybean (Glycine max Merr.) crop rotation. This study explored the effects of soil microbial community structure after soybean and maize crop rotation by designing nine treatments combining three crop rotations (continuous cropping maize or soybean; and maize after soybean) with three fertility treatments (organic compound fertilizer, chemical fertilizer, or without fertilizer). Soil was sampled to 30 cm depth the second year at approximately the middle of the growing season, and was analyzed for physical, chemical, and phospholipid fatty acid (PLFA) profiles. Bacteria was found to be the predominant component of soil microorganisms, which mainly contain the PLFAs i15:0, 16:1 ω 7c, 16:0, 10Me16:0, and 18:1 ω 7c. The concentration of soil gram-negative bacteria from the soybean and maize rotation was less than in soybean continuous cropping when organic fertilizer was applied to both. Crop rotation reduced the percentage of fungi in the soil, among which the effect of organic compound fertilizer application was significantly reduced 24%. The combined crop rotation with organic fertilizer can reduce maximum the percentage of fungi/bacteria. In addition, the content of soil aggregate and organic matter had great influence on gram-positive bacteria and actinomyces, and soil pH had a greater impact on other fungi.
ARTICLE | doi:10.20944/preprints201806.0027.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: fruit juice; debre markos; hygiene; microbial safety
Online: 4 June 2018 (09:56:33 CEST)
Improperly prepared fresh fruit and vegetable juices are recognized as an emerging cause of food borne illnesses. Therefore, this study was aimed at evaluating the microbiological safety of fresh fruit juices marketed in Debre-Markos town and their hygienic conditions of preparations. Thirty six fruit juices samples were collected from 6 cafés and restaurants of Debre-Markos town and analyzed for total aerobic viable bacterial count (TAVBC), total staphylococcal count (TSC), aerobic spore forming bacterial count (ASFBC), total coliform count (TCC), fecal coliform count (FCC), yeast and mould count (YMC). The spread plate method was used for the isolation of microorganisms on appropriate selective media. All isolates were characterized following standard methods. Bacterial and fungal species were isolated following standard methods. Questionnaires were distributed for 30 juice makers to obtain preliminary information on hygienic and safety practices of fruit juice makers. Results show that the mean TAVBC, ASFBC, TSC, yeast and mold, TCC and FCC of mango were 2.2±0.48x106,0.13±0.04x105 ,0.004x105 ,1.1±0.2x106 ,0.15±0.05x105,5.7±3.73x104 and 0.06±0.04x104 cfu/ml respectively. The mean of TAVBC, ASFBC, TSC, YMC, TCC, and FCC of avocado juice were 3.6±0.6x106, 0.08±0.02x105, 0.27±0.07x105, 1.2±0.4x106, 0.02±0.01x105, 6.46±3.7x104, and 0.2±0.1x104 cfu/ml respectively. The bacterial isolates were identified as Staphylococcus aureus, Escherichia coli, Klebsiella spp. Bacillus cereus, Enterobacter spp., Enterococcous spp., Streptococcus spp., and Serratia spp. while the identities of the fungal isolates were Fusarium spp., Mucor spp. and Saccharomyces cerevisiae. The results also showed that the microbial loads of most of the fruit juices were higher than the specifications set for fruit juices sold in the Gulf region and other parts of the world. Most venders obtained fruit from the open market and all juice makers lacked special training in food hygiene and safety. Therefore, regular training and health education on food hygiene and safety is recommended for juice handlers to improve the quality of fresh fruit juices in the study area.
ARTICLE | doi:10.20944/preprints202310.1904.v1
Subject: Biology And Life Sciences, Biology And Biotechnology Keywords: toxicity; microbial biosensor; oxygen electrode; mediator biosensor; microbial biofuel cell (MFC); EC50; toxicity index (T); bacteria Gluconobacter oxydans
Online: 30 October 2023 (12:35:01 CET)
Biosensors based on an oxygen electrode, a mediator electrode and a mediator microbial biofuel cell (MFC) using on the bacteria Gluconobacter oxydans B-1280 have been formed and tested to determine the integral toxicity. G. oxydans bacteria exhibit high sensitivity to the toxic effects of phenol, 2,4-dinitrophenol, salicylic and trichloroacetic acid and a number of heavy metal ions. The system “G. oxydans bacteria – ferrocene – graphite-paste electrode” is superior in sensitivity to biosensors formed using an oxygen electrode and MFC, in particular regarding heavy metal ions (EC50 of chromium (II), manganese (II) and cadmium (II) was 0.8 mg/dm3, 0.3 mg/dm3 and 1.6 mg/dm3, respectively). It has been determined that the period of stable functioning of electrochemical systems during measurements is reduced by half due (from 30 to 15 days) due to changes in the enzyme system of microbial cells when exposed to toxicants. Samples of products made from polymeric materials were analyzed using developed biosensor systems and standard biotesting methods based on inhibiting the growth of duckweed L. minor, reducing the motility of bull sperm and quenching the luminescence of the commercial test system "Ecolum". The developed bioelectrocatalytic systems are comparable in sensitivity to commercial biosensors, which made it possible to correlate the results and identify by all methods a highly toxic sample containing diphenylmethane-4,4'-diisocyanate according to GC-MS data.
ARTICLE | doi:10.20944/preprints202309.0733.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: Farmyard manure; zinc solubilizing microbes; microbial diversity; microbial abundance; Soil DNA sequencing; agricultural inputs; long-term agronomic management
Online: 12 September 2023 (07:20:50 CEST)
Zinc is an important nutrient for plant growth and development. Its availability is influenced by zinc solubilizing microbes (ZSM). Effects of commonly promoted agronomic practices on the abundance of ZSM are so far not well understood. In this study, we assessed the effects of farmyard manure (FYM) application, either sole, or in combination with residue and/or inorganic fertilizer inputs on ZSM community structure using 11 treatments in a long-term (17 years) integrated soil fertility management experiment located in western Kenya, The study was conducted in 2019. Bacterial and fungal community composition (at 0-15 cm depth) was evaluated by amplicon sequencing on an Illumina Miseq platform following the manufacturer’s guidelines. Microbial diversity indices (Shannon, Simpson and Chao1) and statistical analyses were computed using R project packages. Putative ZSM (i.e., the ZSM generally considered to possess the zinc solubilizing capabilities) were clustered in two major clades based on either application or no application of FYM. Sole application of FYM significantly (P<0.05) increased the abundance of several ZSM under maize-tephrosia rotation. In addition, systems with combined application of FYM with other inputs generally showed significantly increasing trends for some ZSM under maize-tephrosia rotation. Moreover, combined application of FYM and P rather than P only significantly increased abundance of some ZSM under maize-monocropping systems. Furthermore, besides affecting ZSM abundance, soil chemical variables involving soil organic carbon (SOC), total N and Olsen P significantly increased with FYM application. This study indicated that management practices like application of FYM that increase SOC, and other soil chemical parameters, also/concomitantly increase ZSM abundance; implying enhanced capacities for microbial-linked zinc availability.
ARTICLE | doi:10.20944/preprints202312.0251.v1
Subject: Agricultural Science And Agronomy, Biology And Life Sciences Keywords: Microplastics; Biochar; Sugarcane biomass; Microbial community; Red soil
Online: 6 December 2023 (05:15:58 CET)
Microplastics pollution in sugarcane areas of China is severe, and reducing their ecological risks is critical. This study aims to explore the effects and mechanisms of microplastics combined with or without biochar on sugarcane growth, soil biochemical properties in red soil by a potted experiment. The results showed that compared with control (CK), microplastic alone treatments reduced the dry biomass of sugarcane, soil pH and the nitrogen (N) and phosphorus (P) contents, obviously decreased the observed_OTUs, Chao1 and Shannon indices of soil total bacteria (16S rRNA gene-based bacteria) while increasing them in phoD-harbouring bacteria. Interestingly, microplastics combined with biochar could alleviate the negative effects of microplastic accumulation on sugarcane growth and soil quality. There were significant differences in the bacterial community compositions among different treatments. Compared with CK, all other treatments significantly decreased the relative abundance of Gemmatimonadota while only microplastic combined with biochar treatments significantly increased the abundance of Subgroup_10 for the 16S rRNA gene, and only microplastic alone treatments significantly increased the relative abundance of Streptomyces for the phoD gene. Moreover, the treatments with microplastics combined with biochar increased the relative abundance of Subgroup_10 and Bradyrhizobium while decreased the IMCC26256 and Streptomyces compared with that in the treatment with microplastics alone. Correlation analysis showed that Subgroup_10 and Bradyrhizobium were significantly positively correlated with sugarcane biomass and several soil properties, while IMCC26256 and Streptomyces were just the opposite. Additionally, different treatments also changed the abundance of potential microbial functional genes. Compared to CK, other treatments increased the abundance of aerobic_ammonia_oxidation, denitrification while decreased the abundance of nitrate_respiration, nitrogen_respiration; meanwhile, these four functional genes involved in N cycling processes were obviously higher in treatments with microplastics combined with biochar than in treatments with microplastic alone. In conclusion, microplastics combined with biochar could alleviate the negative effects of microplastic accumulation on sugarcane growth by improve soil nutrients and microbial community structure and function.
REVIEW | doi:10.20944/preprints202310.0121.v1
Subject: Biology And Life Sciences, Biology And Biotechnology Keywords: Microbial pigments; Biocolors; Organic pigments; Biodegradable pigments; Biotechnology
Online: 3 October 2023 (07:10:28 CEST)
Microbial pigments have many structures and functions with excellent characteristics, such as being biodegradable, non-toxic, and ecologically friendly, constituting an important source of pigments. Industrial production presents a bottleneck in production cost that restricts large-scale commercialization. However, microbial pigments are progressively gaining popularity because of their health advantages. The development of metabolic engineering and cost reduction of the bioprocess using industry by-products opened possibilities for cost and quality improvements in all production phases. We are thus addressing several points related to microbial pigments, including the major classes and structures found, the advantages of use, the biotechnological applications in different industrial sectors, their characteristics, and their impacts on the environment and society.
ARTICLE | doi:10.20944/preprints202309.0593.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: rice; integrated cultivation practices; microbial diversity; environmental factors
Online: 11 September 2023 (05:07:03 CEST)
Integrated cultivation strategies can significantly improve rice yield. However, it is unclear how integrated cultivation practices improve soil microbial diversity and its related mechanism in rice field. Therefore, four integrated cultivation practices i.e., no N application (N0), local farmers’ practice (FP), high-yield and high-efficiency practice (HYEY), and super-high-yield cultivation practice, impacts on soil properties and structure composition of microbial community were explored. Compared with N0, SHY treatment, significantly increased soil alkaline nitrogen and organic matter contents. HYHE and SHY treatments significantly altered soil fungal community and Alpha diversity. Based on Venn diagram analysis, the composition of bacterial communities under all treatments was similar, but with different compositions of fungal communities. Cluster analysis indicates that the Proteobacteria was the absolute dominant group of bacterial communities, and Chloroflexi, Bacteroidetes, and Acidobacteria were the dominant group. Different cultivation methods also led to changes in the main factors affecting soil bacteria and fungi composition. Available potassium and organic matter were the main environmental factors that affected bacteria, with the strong of available potassium on the soil. To sum up, SHY and HYEY were beneficial management options in terms of improved soil fertility Alpha diversity of the soil bacterial community respectively.
REVIEW | doi:10.20944/preprints202308.1878.v1
Subject: Environmental And Earth Sciences, Sustainable Science And Technology Keywords: biolectrochemical system; bioenergy; fuel production; microbial fuel cell
Online: 29 August 2023 (04:33:14 CEST)
The overexploitation of fossil fuels and their negative environmental impact has attracted the attention of researchers worldwide to propose alternatives to produce bioenergy. Microbial fuel cells (MFCs) systems are sustainable biotechnologies that use bacterial activity to break down organic matter while generating bioelectricity. MFCs have bioelectricity from domestic wastewater (DWW), municipal wastewater (MWW), and potato and fruit waste, reducing environmental contamination and decreasing energy consumption and treatment cost. This review focuses on the recent advancements regarding the designs and configurations, the operation mode of MFCs, and their capacity to produce bioelectricity (e.g., 2203 mW/m2) and fuels (i.e., H2: 438.7 mL/g and CH4: 358.7 mL/g, respectively). Besides, this review highlights practical applications, challenges, techno-economic, and life cycle assessments (LCA) of MFCs. Despite MFC's promising biotechnology, great efforts should be made to implement it in real-time and commercialization.
REVIEW | doi:10.20944/preprints202306.2232.v1
Subject: Environmental And Earth Sciences, Waste Management And Disposal Keywords: Bioremediation; Bioreactor systems; Microbial treatment; Environmental impacts; Sustainability.
Online: 30 June 2023 (14:39:23 CEST)
The increasing environmental and human health concerns associated with medical waste have led to the development of environmental biotechnology as a means of mitigating its negative effects. This review paper discusses the various types of medical waste generated in healthcare facilities, as well as the potential environmental and health impacts of improper handling and disposal. It also provides an overview of the different environmental biotechnologies that have been developed to treat medical waste, including bioreactor systems, microbial treatment, and composting. The benefits and drawbacks of these technologies are also discussed. Bioremediation is a promising environmental biotechnology that can be used to treat medical waste contaminated with hazardous chemicals. Case studies from around the world demonstrate the successful application of environmental biotechnologies to medical waste management. These case studies highlight the challenges encountered, the methods used, and the results obtained. The findings of this review paper highlight the need for a comprehensive strategy for managing medical waste that includes environmental biotechnologies. Further research and development are needed to improve the effectiveness, efficiency, and sustainability of medical waste management.
ARTICLE | doi:10.20944/preprints202305.1771.v1
Subject: Biology And Life Sciences, Food Science And Technology Keywords: Silage; corn; wheat; microbial inoculum; amino acids; digestibility
Online: 25 May 2023 (08:40:24 CEST)
Wheat and corn silages are widely used as ruminant feed in Israel due to their availability and cost-effectiveness. To ensure long-term preservation without compromising nutritional quality, effective methods must be employed. Inclusion of additives during harvest and ensiling can enhance efficiency and address preservation challenges. In the current study, the effects of microbial inoculum (MI) and urea on the chemical composition, amino acid profiles, aerobic stability, and in vitro digestibility of wheat and corn silages were investigated. Samples of wheat and corn were subjected to four treatments: control, MI, Urea, and a combination of MI+Urea. The treatments were ensiled in anaerobic conditions and opened after 1, 7, 14, or 28 days. Results showed that additives improved the quality parameters of wheat and corn silages. The inclusion of MI produced the most aerobically stable silages. The inclusion of urea in silages deteriorated aerobic stability. Additives improved in vitro cell wall carbohydrates digestibility in both silages and was the best when MI was combined with urea. These results imply additives could be incorporated in silages to enhance their nutritional value, aerobic stability and digestibility. Nonetheless, increased CP content with additives was not accompanied with parallel increase in amino acids content in corn silage.
ARTICLE | doi:10.20944/preprints202305.1041.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Microbial physiology; Quorum Sensing; Quorum Quenching; Pseudomonas aeruginosa
Online: 15 May 2023 (12:13:55 CEST)
After a time away from the classrooms and laboratories due to the global pandemic, the return to the teaching activities during the semester represented a challenge to both teachers and students. Our particular situation in a Microbial Physiology course was the necessity of imparting in a shorter time, laboratory practices that usually take longer. This article describes a two-week long laboratory exercise that covers several concepts in an interrelated way: conjugation as a gene transfer mechanism, regulation of microbial physiology, production of secondary metabolites, degradation of macromolecules and biofilm formation. Utilizing a Quorum Quenching (QQ) strategy, the Quorum Sensing (QS) system of Pseudomonas aeruginosa is first attenuated. Then, phenotypes regulated by QS are evidenced. QS is a regulatory mechanism of the microbial physiology that relays on signal molecules. QS is related in P. aeruginosa to several virulence factors, some of which are exploited in the laboratory practices presented in this work. QQ is phenomenon by which QS is interrupted or attenuated. We utilized a QQ approach based on the enzymatic degradation of the P. aeruginosa QS signals in order to put in evidence QS-regulated traits that are relevant for our Microbial Physiology course.
ARTICLE | doi:10.20944/preprints202202.0208.v1
Subject: Biology And Life Sciences, Anatomy And Physiology Keywords: aging; intestinal microbiota; dysbiosis; probiotics; microbial co-occurrences
Online: 17 February 2022 (10:59:55 CET)
Age-related alterations in the gut microbiome composition and its impacts on the host’s health have been well described; however, detailed analyses of the gut microbial structure defining ecological microbe-microbe interactions is limited. One of the ways to determine these interactions is by understanding microbial co-occurrence patterns. We previously showed promising abilities of Lactobacillus acidophilus DDS-1 on the aging gut microbiome and immune system. However, the potential of the DDS-1 strain to modulate microbial co-occurrence patterns is unknown. Hence, we aimed to investigate the ability of L. acidophilus DDS-1 to modulate the fecal, mucosal and cecal-related microbial co-occurrence networks in young and aging C57BL/6J mice. Our Kendall’s tau correlation measures of co-occurrence revealed age-related changes in the gut microbiome, which were characterized by reduced number of nodes and associations across sample types when compared to younger mice. After four-week supplementation, L. acidophilus DDS-1 differentially modulated the overall microbial community structure in fecal and mucosal samples as compared to cecal samples. Beneficial bacteria such as Lactobacillus and Akkermansia acted as connectors in aging networks in response to L. acidophilus DDS-1 supplementation. Our findings provided the first evidence of the DDS-1-induced gut microbial ecological interactions revealing the complex structure of microbial ecosystems with age.
REVIEW | doi:10.20944/preprints202112.0069.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: microbiome; golf turf; turfgrasses; biocontrol; microbial communities; endophytes
Online: 6 December 2021 (12:19:16 CET)
Golf courses have a significant environmental impact. High water demands and the intensive use of agricultural chemicals have been a concern for decades and are therefore in the focus of efforts to make golf courses more environmentally sustainable. Products based on modifying or using plant-associated microbiota are one of the fastest growing sectors in agriculture, but their application on turfgrasses on golf courses is so far negligible. In this review, we summarize the limited knowledge on microbiomes of golf turf ecosystems and show that the lack of holistic studies addressing structure and function of golf turf microbiomes, including their responses to intense turf management procedures, is currently the main bottleneck for development and improvement of reliable, well-functioning microbial products. We further highlight the endosphere of turfgrasses, which is easily accessible for microbial cultivation through constant mowing, as the most stable and protected micro-environment. Many grass species do possess endophytic bacteria and fungi that have shown to improve the plants’ resistance towards microbial pathogens and insect pests, and several products using endophyte-enhanced grass varieties are commercially successful. We anticipated that this trend would tee-off on golf courses, too, once a more comprehensive understanding of golf turf microbiomes is available.
REVIEW | doi:10.20944/preprints202109.0228.v1
Subject: Medicine And Pharmacology, Gastroenterology And Hepatology Keywords: gut microbiota; critically ill; faecal microbial transplantation; multiorgan
Online: 14 September 2021 (09:52:56 CEST)
The human gut microbiota consists of bacteria, archaea, fungi, and viruses. It is a dynamic ecosystem shaped by several factors, which play an essential role in both healthy and diseased states of humans. A disturbance of the gut microbiota, also termed “dysbiosis,” is associated with increased host susceptibility to a range of diseases. Because of splanchnic ischaemia, exposure to antibiotics, and/or underlying the disease critically ill patients loose 90% of the commensal organisms in their gut within hours after the insult. This is followed by a rapid overgrowth of potentially pathogenic and pro-inflammatory bacteria altering metabolic, immune, and even neurocognitive functions and turning the gut into the driver of systemic inflammation and multiorgan failure. Indeed, restoring healthy microbiota by means of faecal microbiota transplantation (FMT) in the critically ill is an attractive and plausible concept in intensive care. Yet, available data from controlled studies are limited to probiotics and FMT for severe C. difficile infection or severe inflammatory bowel disease. Case series and observational trials generate hypothesis that FMT might be feasible and safe in immunocompromised patients, refractory sepsis, or severe antibiotic-associated diarrhea in ICU. There is a burning need to test these hypotheses in randomized controlled trials powered for determination of patient-centered outcomes.
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: microbial communities; water quality; Florida Reef Tract; Coral pathogens
Online: 14 May 2021 (16:23:33 CEST)
The Florida Keys, a delicate archipelago of sub-tropical islands extending from the south-eastern tip of Florida, host the vast majority of the only coral barrier reef in the continental United States. Abiotic as well as microbial components of the surrounding waters are pivotal for the health of reef habitats, and thus could play an important role in understanding the development and transmission of coral diseases in Florida. In this study, we analyzed microbial community structure and abiotic factors in waters around the Florida Reef Tract. Both, bacterial and eukaryotic community structure were significantly linked with variations in temperature, dissolved oxygen and total organic carbon values. High abundances of copiotrophic bacteria as well as several potentially harmful microbes, including coral pathogens, fish parasites and taxa that have been previously associated with Red Tide and shellfish poisoning were present in our datasets and may have a pivotal impact on reef health in this ecosystem.
REVIEW | doi:10.20944/preprints202102.0244.v1
Subject: Biology And Life Sciences, Anatomy And Physiology Keywords: microbial communities; synergistic interactions; ecosystem processes; multi-omics
Online: 9 February 2021 (16:59:36 CET)
Mining interspecies interactions remain a challenge due to the complex nature of microbial communities and the need for computational power to handle big data. Our meta-analysis indicates that genetic potential alone does not resolve all issues involving mining of microbial interactions. Nevertheless, it can be used to define the building blocks to infer synergistic interspecies interactions and to limit the search space (i.e., number of species and metabolic reactions) to a manageable size. A reduced search space decreases the number of additional experiments necessary to validate the inferred putative interactions. As validation experiments, we examine how multi-omics and state of the art imaging techniques may further improve our understanding of species interactions’ role in ecosystem processes. Finally, we analyze pros and cons from the current methods to infer microbial interactions from genetic potential and propose a new theoretical framework based on: (i) genomic information of key members of a community; (ii) information of ecosystem processes involved with a specific hypothesis or research question; (iii) the ability to identify putative species’ contributions to ecosystem processes of interest; and, (iv) validation of putative microbial interactions through integration of other data sources.
ARTICLE | doi:10.20944/preprints201808.0250.v1
Subject: Engineering, Chemical Engineering Keywords: EBPR; side-stream; performance comparison; microbial ecology; activity
Online: 14 August 2018 (06:24:23 CEST)
In this study, a full-scale pilot testing was performed with side-by-side operation of a conventional enhanced biological phosphorus removal (EBPR) process and a side-stream EBPR (S2EBPR) process. A comparison of the performance, activities and population dynamics of key functionally relevant populations between the two configurations were carried out. The results demonstrated that, with the same influent wastewater characteristics, S2EBPR configuration showed more effective and stable orthophosphate (PO4-P) removal performance (up to 94% with average effluent concentration down to 0.1 mg P/L) than conventional EBPR, especially when the mixers in side-stream reactor were operated intermittently. Mass balance analysis illustrated that both denitrification and EBPR performance have been enhanced in S2EBPR configuration through diverting primary effluent to anoxic zone and producing additional carbon (~40%) via fermentation in side-stream reactor. Microbial characterization showed that there was no significant difference in the relative abundances of Ca. Accumulibacter (~5.9%) and Tetrasphaera (~16%) putative polyphosphate-accumulating organisms (PAOs) between the two configurations. However, lower relative abundance of known GAOs was observed in S2EBPR configuration (1.1%) than the conventional one (2.7%). A relatively higher PAO activity and increased degree of dependence on glycolysis pathway than TCA cycle was observed in S2EBPR configuration using P release and uptake batch test. Adequate anaerobic solid retention time (SRT) and conditions that generate continuous and slow feeding/production of volatile fatty acid (VFA) with higher composition percentage of propionate in the side-stream reactor of S2EBPR process likely provide a competitive advantage for PAOs over GAOs.
ARTICLE | doi:10.20944/preprints201709.0016.v1
Subject: Biology And Life Sciences, Forestry Keywords: soil; Robinia pseudoacacia; PLFA; stand age; microbial community
Online: 5 September 2017 (15:28:05 CEST)
Phospholipid fatty acids (PLFAs) can be used as biomarkers for qualitative and quantitative analyses of soil microbial community diversity. In this study, we collected soil samples at 10-cm intervals to a depth of 1 m from Robinia pseudoacacia plantations of four different ages (10, 15, 25 and 40 years) in a loess area and analysed the soil microbial community structure by PLFA analysis. A total of 97 PLFAs were detected in soils of R. pseudoacacia plantations of different ages. The individual PLFA contents gradually decreased in the 0- to 40-cm soil layers, with little variation in the 40- to 100-cm soil layers. The individual PLFAs were similarly distributed in the soils of R. pseudoacacia plantations of different ages, and there was a clear variation with stand age and soil depth. The individual PLFA contents in the 0- to 20-cm soil layers were highest for the 25-year-old plantation, while those in the 20- to 40-cm soil layers were relatively high for the 25- and 40-year-old plantations; the 16:0 content was the highest among individual PLFAs. The total PLFA content and the PLFA contents of different microbial groups [bacteria, fungi, Gram-positive bacteria (G+), Gram-negative bacteria (G-) and actinomycetes] initially increased before decreasing in the soils of R. pseudoacacia plantations with increasing stand age, whereas these contents gradually decreased with increasing soil depth; the highest PLFA contents was found in the 25-year-old plantation. The total PLFA content and the contents of fungal, G- and actinomycete PLFAs in the soils of R. pseudoacacia plantations differed significantly among stands of different ages in the 0- to 10-cm, 10- to 20-cm and 30- to 40-cm soil layers, while no significant differences were found in the 20- to 30-cm soil layers; the G+ and bacterial PLFAs contents in each of the 0- to 40-cm soil layers were significantly different. The PLFA ratios between different microbial groups differed among the stands of different ages. The fungi/bacteria ratio showed a “decrease-increase-decrease” trend with stand age, while the G+/G- ratio showed an “increase-decrease” trend. The saturated/monounsaturated PLFA ratio initially decreased before plateauing, while the opposite trend was observed for the cyclopropyl/precursor ratio. The PLFA contents of different microbial groups were ranked as follows: bacteria > G- > G+ > actinomycetes > fungi. In the principle component analysis, 18:1ω9c, 10Me18:0, i17:0, a17:0, 18:1ω7c, 18:1ω5c and 18:0 made the greatest contribution to principal component 1, and a14:0, i14:0 3OH, i14:0, i14:1ω7c and 14:0 made the greatest contribution to principal component 2. In conclusion, soil nutrient status and other soil eco-environmental stress factors should be considered in 10- to 25-year-old (particularly ~15-year-old) plots for the management of R. pseudoacacia plantations to prevent forest soil degradation and improve forest stand quality, thereby achieving better soil and water conservation and environmental improvement in R. pseudoacacia plantations.
ARTICLE | doi:10.20944/preprints202311.1980.v1
Subject: Public Health And Healthcare, Public, Environmental And Occupational Health Keywords: household washing machines; microbial contamination; metagenomics; pathogenic bacteria; biofilm
Online: 1 December 2023 (03:11:19 CET)
Washing machines are one of the tools that bring great convenience to people's daily lives. However, washing machines that have been used for a long time often develop issues such as odor and mold, which can pose health hazards to consumers. There exists a conspicuous gap in our understanding of the microorganisms that inhabit the inner workings of washing machines. In this study, samples were collected from 22 washing machines in Shanghai, China, including both water eluted from different parts of washing machines and biofilms. Quantitative qualitative analysis was performed using fluorescence PCR quantification and microbial communities were characterized by high throughput sequencing (HTS). It showed that the microbial communities in all samples were predominantly composed of bacteria, and they have a strong adhesion ability in the washing machine environment. HTS results showed that in the eluted water samples, the bacteria mainly included Pseudomonas, Enhydrobacter, Brevibacterium and Acinetobacter. On the contrary, in biofilm samples, Enhydrobacter and Brevibacterium were the predominant bacterial microorganisms. Correlation analysis results revealed that microbial colonies in washing machines were significantly correlated with years of use and the type of detergent used to clean the washing machine. As numerous pathogenic microorganisms can be observed in the results, effective preventive measures and future research are essential to mitigate these health problems and ensure the continued safe use of these household appliances.
ARTICLE | doi:10.20944/preprints202306.0900.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: Corneal blindness; microbial keratitis; Pythium insidiosum; therapeutic penetrating keratoplasty
Online: 13 June 2023 (08:51:35 CEST)
Pythium insidiosum(PI) can cause sight threatening keratitis which is managed commonly by performing penetrating keratoplasty. This article is a retrospective review to assess outcomes of keratoplasty performed in patients diagnosed with PI keratitis. (2) Methods: Pre-operative, intra operative and post-operative data of patients diagnosed with PI keratitis and who underwent keratoplasty for their condition from January 2020 to December 2021 were col-lected from the central patient database of a tertiary eye care hospital in India. The data were an-alyzed for anatomic success, elimination of infection, graft survival, incidence of repeat kerato-plasty, final visual acuity and varied complications. (3) Results: In total, 16 eyes underwent pene-trating keratoplasty for PI keratitis during the study period. Mean time to keratoplasty from on-set of symptoms was 31.3 days and mean graft size was 10.4 mm. Nine out of the 16 cases had recurrence of infection following surgery, six of which required a repeat keratoplasty for elimina-tion of infection. Out of these 6 patients, one patient underwent 2 repeat keratoplasties. Mean graft size for repeat keratoplasty performed in recurrent cases was 11.7 mm. Globe was successfully salvaged in 14 out of 16 patients (87.5 %). Endo-exudates, graft infiltration, graft dehiscence, secondary glaucoma and retinal detachment were the various complications noted after kerato-plasty. (4) Conclusion: Keratoplasty remains the choice of treatment in PI keratitis, however re-currence of disease and graft failure are common. Large sized grafts, meticulous per-operative removal of infection, adjuvant cryotherapy, and intraoperative and post-operative use of antibi-otics can help in improving outcome of keratoplasty in these patients.
ARTICLE | doi:10.20944/preprints202305.2095.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: biocontrol; natural products; phytopathogens; microbial metabolites; entomopathogens; endophytic fungi.
Online: 30 May 2023 (09:02:51 CEST)
The genus Beauveria include important entomopathogenic and endophytic fungi, among them, Beauveria bassiana is the most studied species. However, there are few knowledge regarding their antimicrobial activity. The current research has been conducted to evaluate in vitro antagonistic activity of B. bassiana and the antimicrobial efficacy of its Exo and Endo metabolites against Bacillus cereus, B. megaterium, Clavibacter michiganensis (gram positive bacteria, G+ve), Xanthomonas campestris, Pseudomonas aeruginosa and P. fluorescence (gram negative bacteria, G-ve). In addition, Solid-phase microextraction (SPME) was coupled to Gas Chromatography-Mass Spectrometry (GC/MS) to qualitatively measure the volatile organic compounds (VOCs) metabolic profile of the most efficient studied isolate of B. bassiana. The obtained results showed that, the isolate UniB2439-3 has promising antibacterial effect against most of studied target bacteria. SPME-GC/MS analysis of VOCs revealed the presence of ethanol; butanal,2-methyl; 2,4-dimethyl-1-heptene; octane, 4-methyl and β-elemene as the main dominant bioactive compounds. The outgoing results explicated that the efficient isolate of B. bassiana can be potentially used as a biocontrol agent against several bacteria especially G+ve ones.
ARTICLE | doi:10.20944/preprints202305.2067.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Metagenomics; red algae; microbial diversity; algal-polysaccharide-degrading enzymes
Online: 30 May 2023 (07:33:37 CEST)
Macroalgae and macroalgae-associated bacteria together constitute the most efficient metabolic cycling system in the ocean. Their interactions, especially the responses of macroalgae-associated bacteria communities to algae in different geographical locations, is mostly unknown. In this study, metagenomics was used to analyze the microbial diversity and associated algal polysaccharide-degrading enzymes on the surface of red algae among three remote regions. There were significant differences in the macroalgae-associated bacteria community composition and diversity among the different regions. At the phylum level, Proteobacteria, Bacteroidetes, and Actinobacteria had a significantly high relative abundance among the regions. From the perspective of species diversity, samples from China had the highest macroalgae-associated bacteria diversity, followed by those from Antarctica and Indonesia. In addition, in the functional prediction of the bacterial community, genes associated with amino acid metabolism, carbohydrate metabolism, energy metabolism, metabolism of cofactors and vitamins, and membrane transport had a high relative abundance. Canonical correspondence analysis and redundancy analysis of environmental factors showed that, without considering algae species and composition, pH and temperature were the main environmental factors affecting bacterial community structure. Furthermore, there were significant differences in algal polysaccharide-degrading enzymes among the regions. Samples from China and Antarctica had high abundances of algal polysaccharide-degrading enzymes, while those from Indonesia had extremely low abundances. The environmental differences between these three regions may impose a strong geographic differentiation regarding the biodiversity of algal microbiomes and their expressed enzyme genes. This work expands our knowledge of algal microbial ecology, and contributes to an in-depth study of their metabolic characteristics, ecological functions, and applications.
ARTICLE | doi:10.20944/preprints202304.0134.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: biocontrol; natural products; phytopathogens; microbial metabolites; entomopathogens; endophytic fungi
Online: 10 April 2023 (03:06:01 CEST)
The genus Beauveria include important entomopathogenic and endophytic fungi, among them, B. bassiana is the most studied species. However, there are few knowledge regarding their antimicrobial activity. The current research has been conducted to evaluate in vitro antibacterial efficacy of five isolates of B. bassiana against Bacillus cereus, B. megaterium, B. mojavensis, Clavibacter michiganensis (gram positive bacteria, G+ve), Xanthomonas campestris, X. vesicatoria, Escherichia coli, Pseudomonas aeruginosa and P. fluorescence (gram negative bacteria, G-ve). In addition, chemical composition of the principal diffusible metabolites and volatile organic compounds (VOCs) of the most efficient studied isolate of B. bassiana has been carried out using GC-MS analysis. The obtained results showed that, the isolate UniB2439-3 has promising antibacterial effect against most of studied target bacteria. GC-MS analysis of diffusible metabolites detected the presence of hexanedioic acid, bis(2-ethylhexyl) ester as the main compound in the cell-free culture filtrate. Furthermore, GC-MS analysis of VOCs revealed the presence of ethanol; butanal,2-methyl; 2,4-dimethyl-1-heptene; octane, 4-methyl and β-elemene as the main dominant bioactive compounds. The outgoing results explicated that, the isolates of B. bassiana have promising antibacterial activity which could be correlated to their diffusible and VOCs metabolites. Therefore, the selected isolate can be potentially used as a biocontrol agent against several bacteria especially G+ve ones. Taking in consideration that the antibiotics are forbidden in agriculture in many countries worldwide, search for possible natural alternatives as efficient antimicrobial agents are highly interesting.
ARTICLE | doi:10.20944/preprints202211.0006.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: Neural network; Biochemical Oxygen demand; Biosensor; Microbial Fuel Cell
Online: 1 November 2022 (01:22:10 CET)
Biochemical oxygen demand (BOD) is one of the most important factors to consider when evaluating water contamination. BOD5 is the amount of oxygen consumed in five days by microorganisms that oxidize biodegradable organic materials in an aerobic biochemical manner. The primary objective of this effort is to use microbial fuel cells (MFCs) to shorten the time required for BOD5 measurements. We created a regression artificial neural network (AI), and the predictions we obtained for BOD5 measurements were taken over 6 – 24 hours with an average error of just 7%. The outcomes demonstrated by our AI MFC/BES BOD5 sensor’s viability for use in real-world scenarios.
SHORT NOTE | doi:10.20944/preprints202111.0374.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: Stable Isotope Probing; RNA; density gradient; ultracentrifugation; microbial ecology
Online: 22 November 2021 (10:41:51 CET)
Cesiumtrifluoroacetate (CsTFA) is a key chemical for RNA-based stable isotope analyses to link the structure and function of microbial communities. We report a protocol to easily synthesize CsTFA from Cesiumcarbonate (Cs2CO3) and Trifluoroacetate (TFA) and show that self-synthesized CsTFA behaves similar to commercial CsTFA in the separation of isotopically labelled and unlabelled E. coli RNA.
ARTICLE | doi:10.20944/preprints202109.0128.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: Poisonous plants; soil microbial communities; Stellera chamaejasme; Elymus nutans
Online: 7 September 2021 (12:17:21 CEST)
Stellera chamaejasme L. is a fast-spreading unpalatable poisonous plant that grows in the alpine grasslands of the Qinghai-Tibetan Plateau (QTP). The impacts of unpalatable plant species spread on animal health and plant community have been well studied, but studies into their effects on belowground organisms and processes are rare. We carried out a soil metabarcoding study using Illumina MiSeq sequencing to investigate whether the soil bacteria and fungi communities of Stellera are different to the soil microbiome of neighboring palatable grass Elymus nutans Griseb. Total carbon and nitrogen, the ratio of carbon to nitrogen, ammonium nitrogen, and microbial biomass carbon were all significantly greater in Stellera soil compared to Elymus soil, while no significant differences were observed for gravimetric soil moisture, pH or nitrate nitrogen. There were no significant differences in bacterial and fungal abundance between Stellera and Elymus soil. The bacterial species richness was significantly lower in Stellera soil but no significant difference was observed for fungal species richness. The beta diversity and community composition of bacteria and fungi were markedly different between soils. The presence of bacterial phyla Actinobacteria and Verrucomicrobia, and fungal phyla, Basidiomycota and Glomeromycota, were significantly greater under Stellera soil. This study demonstrated that the spread of undesirable unpalatable plants can potentially disrupt existing plant-soil-microbe associations with potential consequences for grassland soil biodiversity and ecosystem functioning.
REVIEW | doi:10.20944/preprints202009.0650.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: biofertilizers; sustainable agriculture; plant growth-promoting rhizobacteria; microbial formulations
Online: 26 September 2020 (16:48:22 CEST)
The world’s population is increasing and so are agricultural activities to match the growing demand for food. Conventional agricultural practices generally employ artificial fertilizers to increase crop yields, but these have multiple environmental and human health effects. For decades, environmentalists and sustainability researchers have focused on alternative crop fertilization mechanisms to address these challenges, and biofertilizers have constantly been researched, recommended, and even successfully-adopted for several crops. Biofertilizers are microbial formulations made of indigenous plant growth-promoting rhizobacteria (PGPR) which can naturally improve plant growth either directly or indirectly, through the production of phytohormones, solubilization of soil nutrients, and production of iron-binding metabolites; siderophores. Biofertilizers, therefore, hold immense potential as tools for sustainable crop production especially in the wake of climate change and global warming. Despite the mounting interest in this technology, their full potential has not yet been realized. This review updates our understanding of the PGPR biofertilizers and sustainable crop production. It evaluates the history of these microbial products, assesses their present state of utilization, and also critically propounds on their future prospects for sustainable crop production. Such information is desirable to fully evaluate their potential and can ultimately pave the way for their increased adoption for crop production.
REVIEW | doi:10.20944/preprints202009.0449.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: oleaginous microorganisms; microbial lipids; lignocellulose pretreatment; enzymatic hydrolysis; inhibitors
Online: 19 September 2020 (05:16:42 CEST)
The microorganisms able of accumulating lipids in high percentages, known as oleaginous microorganisms, have been widely studied as an alternative for producing oleochemicals and biofuels. Microbial lipid, so called Single Cell Oil (SCO), production depends on several growth parameters, including the nature of the carbon substrate, which must be efficiently taken up and converted into storage lipid. Οn the other hand, substrates considered for large scale applications must be abundant and of low acquisition cost. Among others, lignocellulosic biomass is a promising renewable substrate containing high percentages of assimilable sugars (hexoses and pentoses). However, it is also highly recalcitrant and therefore it requires specific pretreatments in order to release its assimilable components. The main drawback of lignocellulose pretreatment is the generation of several by-products that can inhibit the microbial metabolism. In this review, we discuss the main aspects related to the cultivation of oleaginous microorganisms using lignocellulosic biomass as substrate, hoping to contribute to the development of a sustainable process for SCO production in the near future.
Subject: Chemistry And Materials Science, Organic Chemistry Keywords: secondary metabolites; microbial diversity; metabolomics; molecular network; marine bacteria
Online: 19 October 2019 (02:01:18 CEST)
Rocas Atoll is a unique environment in the Equatorial Atlantic Ocean, hosting a large number of endemic species and studies on the chemical diversity emerging from this biota are rather scarce. Therefore, the present work aims to assess the metabolomic diversity and pharmacological potential of the microbiota from Rocas Atoll. A total of 76 bacteria were isolated and cultured in liquid culture media to obtain crude extracts. About one third (34%) of these extracts were considered cytotoxic against human colon adenocarcinoma HCT-116 cell line. 16S rRNA gene sequencing analysis revealed that the bacteria producing cytotoxic extracts are mainly from the Actinobacteria phylum, including Streptomyces, Salinispora, Nocardiopsis and Brevibacterium genera, and in a smaller proportion from Firmicutes phylum (Bacillus). The search in the GNPS spectral library unveiled a high chemodiversity being produced by these bacteria, including rifamycins, antimycins, desferrioxamines, ferrioxamines, surfactins, surugamides, staurosporine and saliniketals, along with several unidentified compounds. Using an original approach, molecular network successfully highlighted groups of compounds responsible for the cytotoxicity of crude extracts. DEREPLICATOR+, a recently developed in silico tool (GNPS), allowed the identification of derivatives of the macrolide novonestimycin, as the cytotoxic compounds into the extracts produced by Streptomyces BRB-298 and BRB-302. Overall, these results highlighted the pharmacological potential of bacteria from this singular Atoll.
ARTICLE | doi:10.20944/preprints201906.0053.v1
Subject: Biology And Life Sciences, Biology And Biotechnology Keywords: Anammox; biofilms; granulation; methanogens; microbial ecology; sludge granules; wastewater
Online: 7 June 2019 (03:48:36 CEST)
As the global demand for water increases, so does the quantity of wastewater requiring treatment. Due to a relatively low carbon footprint, compared with conventional wastewater treatment technologies, anaerobic digestion (AD) was identified in the 1970s as a forerunner in the push for sustainability, when interest in sustainable technologies and renewable energy sources was first sparked. AD technology development ultimately resulted in the discovery of the ‘anaerobic granule’. It is a spontaneously-forming bio-aggregate of microbial cells capable of digesting pollutants and producing methane-rich biogas as a renewable source of bioenergy. The high settling velocity of such granules meant that AD systems could be operated as high-rate treatment processes, because the active, relatively-slow-growing, pollutant-removing biomass would be retained inside, and not washed out of, even bioreactors operated at extremely high volumetric loading rates. In the intervening years the emergence of the anaerobic ammonium oxidising (anammox) granule, aerobic granule, hydrogenic granule, oxygenic photogranule, and many other functionally-specialised granules, has opened new opportunities in wastewater treatment biotechnology. Whilst environmental engineering based around wastewater treatment is still a growing field of research and implementation, the granule (in all forms) is starting to catch the attention of microbial ecologists. It is a self-immobilised biofilm, with many of the properties of ‘conventional’ biofilms formed in Nature. However, as a single entity, a granule represents an entire community of microorganisms, competing or functioning cooperatively or in syntrophy. Together, inside a bioreactor, granules perform side-by-side arguably representing a meta-organism. Granules are gaining traction as the perfect samples for high-throughput studies on fundamental ecological concepts. Granular biofilms can be used to test hypotheses around drivers of diversity, community assembly, biofilm formation and maturation, community expansion and succession, community stress response, among others. This review outlines the history of three of the most influential types of granules: the anaerobic (methanogenic), aerobic and anammox granule. The main biochemical processes found in each type; their primary characteristics; and the typical makeup of the microbial community underpinning the processes are compared. Finally, the adoption of granules as the perfect ‘playground’ for experiments in microbial ecology is reviewed.
ARTICLE | doi:10.20944/preprints201810.0382.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: intercropping; microbial community; high throughput sequencing; nifH gene; sugarcane
Online: 17 October 2018 (10:20:19 CEST)
Intercropping significantly improves land use efficiency and soil fertility. This study examines the impact of three cultivation systems (monoculture sugarcane, peanut-sugarcane and soybean-sugarcane intercropping) on soil properties and diazotrophs. Sugarcane rhizosphere soil was sampled from the farmers’ field. Soil properties and nifH gene abundance were analyzed by high throughput sequencing. Moreover, a total of 436,458 nifH gene sequences were obtained and classified into the 3201 unique operational taxonomic units (OTUs). Maximum unique OTUs resulted with soybean-sugarcane intercropping (<375). The dominant groups across all cultivation were Alpha-proteobacteria and Beta-proteobacteria. On the basis of microbial community structure, intercropping systems were more diverse than monoculture sugarcane. In the genus level, Bradyrhizobium, Burkholderia, Pelomonas, and Sphingomonas were predominant in the intercropping systems. Moreover, diazotrophic bacterial communities of these cultivation systems were positively correlated to the soil pH and soil enzyme protease. Moreover, low available P recovered from intercropping system showed a strong correlation with higher nutrient uptake activity of soil microbes. Based on the results, our investigation concluded that intercropping system caused a positive effect on the growth of diazotrophic bacterial communities and it might boost the soil fertility and this kind of study helps to develop an eco-friendly technology for sustainable sugarcane production.
ARTICLE | doi:10.20944/preprints201709.0048.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: microbial contamination; bacteria; contamination sources; small watershed; Tibetan Plateau
Online: 12 September 2017 (16:01:26 CEST)
Microbial contamination is now more common than chemical contamination in Tibet, and water-borne microbes can cause a number of diseases that threaten public health. Thus, in order to clarify the spatiotemporal distribution of bacteria in small watersheds for which there is no data in Tibet, we set up four sampling points along an upstream-downstream transect of the Xincang River Basin. We collected 239 water samples in 2014 and 2015, and evaluated their total constituent numbers of bacteria (TB) and coliforms (TC). The results of this study show that the microbial contamination of the Xincang River Basin is mild-to-moderate in terms of TB and TC contents, and that these concentrations vary significantly in different seasons. Results show that in summer TB and TC concentrations in the downstream section of this river were highest and that microbial contamination was most serious. Data also demonstrate that precipitation is the most important factor underlying increases in TB and TC concentrations during the summer months; both these variables are significantly correlated with precipitation, while animal husbandry and domestic sewage are the main sources of microbial contamination overall. The results of this study are likely to reflect the basic characteristics of small watersheds for which there is no data to some extent, and are thus of significant practical importance for protecting their ecological environments and promoting sustainable development.
ARTICLE | doi:10.20944/preprints201609.0056.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: green manure; soil microbial communities; crop health; Illumina sequencing
Online: 18 September 2016 (08:56:53 CEST)
Green manure could improve soil nutrients and crop production, playing a significant role in sustainable agriculture. However, the impacts of green manure on crop health and the roles soil microbial communities play in the process haven’t been clarified clearly yet. In this study, we investigated soil microbial community composition and structure in four tobacco farmlands, which were treated with different green manure (control, ryegrass, pea and rape), using 16S rRNA gene amplicons sequencing. Results showed that green manure had significant impacts on soil properties, microbial communities and tobacco health. First, soil total C, N and Ca content increased significantly in groups treated with green manure than control. Second, soil community diversity was significantly higher in groups treated with green manure. Third, green manure especially ryegrass, decreased tobacco disease (bacterial wilt) rate dramatically, and the process might be mediated by soil microbial communities. On the one hand, several microbial populations were found to be potentially disease inducible or suppressive. For example, the abundances of Dokdonella and Rhodanobacter were positively correlated to tobacco disease rate, while Acidobacteira_Gp4 and Gp6 had negative correlations with tobacco disease. On the other hand, soil microbial communities were shaped by soil properties (e.g., pH, C and N content). In conclusion, our research showed that green manure could increase soil nutrients directly, and further improve tobacco health mediated by soil microorganisms, which may shed light on revealing interactions among soil properties, microorganisms and plants.
ARTICLE | doi:10.20944/preprints202310.1689.v1
Subject: Biology And Life Sciences, Biology And Biotechnology Keywords: marine yeast; microbial phylogenetics; bioactivity; antioxidant; biological control; tyrosinase inhibition
Online: 26 October 2023 (11:10:54 CEST)
Marine yeasts have versatile applications in industrial, medical and environmental fields, but have received little attention compared to terrestrial yeasts and filamentous fungi. In this study, a phylogenetic analysis of 11 marine-derived yeasts was conducted using internal transcribed spacers and nuclear large subunit rDNA, and their bioactivities, such as antioxidant, antibacterial, and tyrosinase inhibition activities, were investigated. The 11 marine-derived yeasts were identified to belong to seven species including Geotrichum candidum, Metschnikowia bicuspidata, Papiliotrema fonsecae, Rhodotorula mucilaginosa, Vishniacozyma carnescens, Yamadazyma olivae, and Yarrowia lipolytica, and three strains of these were candidates for new species of the genera Aureobasidium, Rhodotorula, and Vishniacozyma. Most extracts showed antioxidant activity, whereas seven strains exhibited antibacterial activities against Bacillus subtilis. Only Aureobasidium sp. US-Sd3 among the 11 isolates showed tyrosinase inhibition. Metschnikowia bicuspidata BP-Up1 and Yamadazyma olivae K2-6 showed notable radical-scavenging activity, which has not been reported previously. Among the isolates, Aureobasidium sp. US-Sd3 exhibited the highest antibacterial and tyrosinase inhibitory activities. Overall, our results demonstrate the potential of marine-derived yeasts as a source of bioactive compounds for improving industrial applications.
REVIEW | doi:10.20944/preprints202310.1117.v1
Subject: Engineering, Bioengineering Keywords: Metabolic engineering; CO2 fixation; feedstock; biomanufacturing; electrochemical catalysis; microbial electrosynthesis
Online: 18 October 2023 (08:17:15 CEST)
Microbial cell factories offer an eco-friendly alternative for transforming raw materials into commercially valuable products, primarily because of their reduced carbon impact compared to conventional industrial procedures. These systems often depend on lignocellulosic materials, mainly pentose and hexose sugars, richly available carbon reservoirs. Nevertheless, these resources might not always be efficient due to the limited supply, significant cost, and other considerable obstacles. One major hurdle when working with sugars derived from lignocellulosic biomass, especially glucose, is balancing carbon allocation to satisfy energy, cofactor, and other essential component needs for cellular proliferation while maintaining a robust yield. Furthermore, nearly half or more of this carbon is inevitably lost as CO2 during the biosynthesis processes, which serves to generate the energy necessary for maintaining cell growth and other regular metabolic activities. This carbon loss lowers the theoretical production yield and compromises the benefit of reducing greenhouse gas emissions – a fundamental advantage of biomanufacturing. This review paper posits the perspectives of using CO2 from atmosphere, industrial wastes, or the exhausted gases generated in microbial fermentation as a feedstock for biomanufacturing. Both one-step direct CO2 fixation or two-step indirect CO2 fixation and conversion strategies are discussed, which can minimize the carbon loss, significantly increase the carbon yield, and eventually achieve the carbon-neutral or -negative goals. The one-step strategy uses novel metabolic pathway design and engineering approaches to directly fix the CO2 via the pathway toward the synthesis of the desired fermentation products. Due to the limitation of the yield and efficiency in one-step CO2 fixation, the two-step strategy aims to completely avoid carbon loss in biomanufacturing by integrating a first electrochemical fixation of the exhausted CO2 into C1/C2 products such as formate, methanol, acetate, and ethanol and a second fermentation unit to utilize the CO2-derived C1/C2 chemicals or co-utilize both C5/C6 sugars and C1/C2 chemicals for product formation. The great potentials and challenges of using CO2 as a feedstock for further biomanufacturing are also discussed.
ARTICLE | doi:10.20944/preprints202309.1337.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: no-tillage; intercropping; microbial community; soil properties; soil enzyme activities
Online: 20 September 2023 (03:20:40 CEST)
No-till and cereal-legume intercropping have been recognized as favorable cropping practices to increase crop yields while maintaining soil quality in arid and semiarid environment, but the bio-logical mechanisms are poorly understood. The present study was to determine the response of soil properties, enzyme activities, and microbial community diversity and composition in mono- and inter-cropping under conventional and no-tillage conditions. We initiated a field experiment in Wuwei, a typical arid area of China, in 2014. Soil was sampled in August 2022 and, yields, soil properties, enzyme activities, and the microbial community diversity and composition were de-termined in the maize and pea strips in inter- and mono-cropping systems. Results revealed that the maize and pea strips in the no-till intercropping significantly increased yields, total and or-ganic carbon stocks, decreased NO3--N, and obtained the highest total and organic P in the soil. The α- and β-diversity of archaea and eukaryotes were significantly affected by planting patterns, while α- and β-diversity of the bacterial community were significantly affected by tillage practices. Both no-tillage and intercropped maize significantly increased the abundance of archaea phylum Thaumarchaeota and bacterial phylum Nitrospirae, benefiting nitrogen fixation of intercropped pea from the atmosphere under the no-tillage cereal/legume intercropping. No-till intercropping was conducive to the accumulation of organic carbon, while decreasing the abundance of Prote-obacteria, Acidobacteria, and Verrucomicrobia. Limited soil enzyme activities (ACP, ALP, DP, NAG, BG, AG, CB) led to decreases in organic carbon turnover and utilization. Intercropping al-tered soil microbial community diversity and composition due to changes in soil properties and enzyme activities. These findings suggest that no-tilled cereal-legume intercropping is a sustaina-ble cropping practice for improving soil properties and enhancing microbial (archaea, bacterial, Eukaryota) diversity, but the long-term persistence is not conducive to rapid turnover of soil nu-trients due to limited enzyme activities.
ARTICLE | doi:10.20944/preprints202308.0132.v1
Subject: Environmental And Earth Sciences, Soil Science Keywords: microbial fertilizer; humic acid; Attapulgite clay; soil fertility; soil salinity
Online: 2 August 2023 (03:11:45 CEST)
Saline soil from the coast is a valuable resource that is readily available. It is also a valuable resource for reserving arable land. It has been demonstrated that adding organic fertilizers to salinized soils can effectively enhance them. However, since the improvement of saline soils cannot be achieved by a single measure, the effects of compound measures of organic fertilizers combined with mineral elements, humic acid, are significant and might be examined in depth. In order to explore the effects of various measures on the features of pH, electrical conductivity (EC), and nutrient changes in coastal salinized soils in Yancheng, Jiangsu Province, a ryegrass-alfalfa rotation with organic fertilizer as well as compound measures was designed. The findings indicated that the total nitrogen (TN) content of the soil increased and that all organic fertilizer composites decreased the electrical conductivity of the surface soil. However, the organic fertilizer with microbial fertilizer and humic acid was especially effective at regulating the pH and electrical conductivity of the surface soil during the time when salts were prone to accumulating. In conclusion, our findings point to new approaches to lowering salinity and boosting fertility in coastal saline soils: organic fertilizer with microbial fertilizers and humic acid, as well as organic fertilizer with Attapulgite clay.
ARTICLE | doi:10.20944/preprints202307.0022.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Silver/zinc oxide nanoparticles; Semiconductor; Microbial biosynthesis; Photodegradation; Cytotoxicity; Antibacterial
Online: 3 July 2023 (08:37:44 CEST)
The biological synthesis of nanoparticles has been emerging as an environmentally benign and eco-friendly method owing to its cost-effectiveness and high efficiency. Recently, the biological synthesis of semiconductor and metal-doped semiconductor nanoparticles with enhanced photocatalytic degradation efficiency and anticancer and antibacterial properties have gained tremendous attention. In pursuit of this purpose, for the first time, we biosynthesized zinc oxide (ZnO) and silver/ZnO nanocomposites (NCs) as semiconductor and metal-doped semiconductor nanoparticles, respectively, using the cell-free filtrate (CFF) of Lysinibacillus sphaericus bacterium. The biosynthesized ZnO and Ag/ZnO were characterized by various techniques such as ultraviolet-visible spectroscopy, X-ray diffraction, Fourier-transform Infrared spectroscopy, Field-emission scanning electron microscopy, transmission electron microscopy, and photoluminescence spectroscopy. The photocatalytic degradation potential of these semiconductor/metal-semiconductor nanoparticles was evaluated against the degradation of azo dye methylene blue (MB) under simulated solar irradiation. Ag/ZnO showed 90.7 ± 0.91% photocatalytic degradation of MB, compared to 50.7 ± 0.53% by ZnO in 120 min. The cytotoxicity of ZnO and Ag/ZnO on human cervical HeLa cancer cells was determined using an MTT assay. Both nanomaterials exhibited cytotoxicity in a concentration-dependent and time-dependent manner on HeLa cells. The antibacterial activity was also determined against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus). Compared to ZnO, Ag/ZnO NPs showed higher antibacterial activity. Hence, the biosynthesis of semiconductor nanoparticles could be a promising strategy for developing hybrid metal/semiconductor nanomaterials for different biomedical and environmental applications.
ARTICLE | doi:10.20944/preprints202306.2049.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Pseudomonas aeruginosa; bioelectrochemical systems; fermentation; 1,3-propanediol; microbial fuel cells
Online: 28 June 2023 (14:46:16 CEST)
The ability of some bacteria to perform Extracellular Electron Transfer (EET) has been explored in bioelectrochemical systems (BES) to obtain energy or chemicals from pure substances or residual substrates. Here, a new pyoverdine-producing Pseudomonas aeruginosa strain was isolated from a MFC biofilm oxidizing glycerol, a by-product of biodiesel production. Strain EL14 was investigated to assess its electrogenic ability and products. In an open circuit system (fermentation system) EL14 was able to consume glycerol and produce 1,3-propanediol, an unusual product from glycerol oxidation in P. aeruginosa. The microbial fuel cell (MFC), EL14 reached a current density of 82.4 mA m-2, during the first feeding cycle, then drops sharply as the biofilm falls off. Cyclic voltammetry suggests electron transfer to the anode occurrs indirectly, i.e., through a redox substance, with redox peaks at 0.22 and -0.45 V (vs Ag/AgCl) and directly probably by membrane redox-proteins with redox peak at 0.05 V (vs Ag/AgCl). EL14 produced added-value bioproducts, acetic and butyric acids, as well as 1,3 propanediol, in both fermentative and anodic conditions. However, the yield of 1,3-PDO from glycerol was enhanced from 0.57 to 0.89 (mol of 1,3-PDO mol-1 of glycerol) under MFC conditions compared with the fermentation. This result was unexpected since successful 1,3-PDO production is not usually associated with the P. aeruginosa glycerol metabolism. By comparing EL14 genomic sequences related to the 1,3-PDO biosynthesis with reference P. aeruginosa strains, we observed that strain EL14 has three copies of dhaT gene (1,3-propanediol dehydrogenase a different arrangement compared to other Pseudomonas isolates). Thus, this work functionally characterizes a bacterium never before associated to 1,3-PDO biosynthesis, indicating its potential for converting a by-product of the biodiesel industry into an emerging chemical product.
ARTICLE | doi:10.20944/preprints202306.1755.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: Biogas slurry; Drip; Nutrigation; Spinach; Phenology; Nutrient uptake; Microbial properties
Online: 26 June 2023 (07:06:06 CEST)
To achieve higher crop yields and maintain environmental conservation, it becomes imperative to adopt novel agricultural methods that improve both the quantity and quality of produce. The above study focused on investigating the effectiveness of integrated use of biogas slurry (BS) and inorganic nutrigation on spinach growth and nutrient uptake through drip irrigation. Under field conditions and using a split plot design, spinach was cultivated with seven different treatments: biogas slurry nutrigation (BSN) (T1), integrated inorganic + organic nutrigation: 40% Recommended dose of fertilizer (RDF) +BSN (T2), 60% RDF +BSN (T3), 80% RDF +BSN(T4), 100% RDF(T5), slurry broadcasting (SB) (T6), and control(T7). The results showed that spinach grown with T4 80% RDF +BSN exhibited optimum plant height and leaf count compared to spinach under other treatments and was at par with T5 100% RDF for crop parameters. T5 treated plants demonstrated the longest roots, followed by T4 treated plants. The biomass produced by T4 was at par with T5 in the first (T4= 4.60 tonha-1, T5 =4.67 tonha-1) and second harvesting(T4= 6.69 tonha-1, T5 =6.89 tonha-1).In terms of macronutrient content in spinach leaves, significant differences were found only for nitrogen (N),potassium (K), while the phosphorus contents were not significantly influenced. Incorporating biogas slurry into the soil modifies microbial enzyme activities, specifically dehydrogenase and phosphatase. Normally, alkaline phosphatase shows greater activity than acidic phosphatase, but the addition of biogas slurry equalized the enzymatic activity of both, establishing a harmonized enzymatic profile. Fertilizing spinach with integrated Biogas slurry nutrigation + inorganic nutrigation not only improves growth and development to a similar extent as inorganic fertilizer but also enhances the nutrient content of the spinach, contributes to environmental preservation, and reduces production costs.
TECHNICAL NOTE | doi:10.20944/preprints202305.0835.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: degraded metagenome; shotgun metagenomics; stomach acid; microbial identification; percent identity
Online: 11 May 2023 (09:25:18 CEST)
Metagenomics have opened our eyes to the otherwise enigmatic microbial consortia that relies on different human body niches that impact on disease pathogenesis. This work originally aims to re-analyse a public shotgun metagenomics dataset to glean insights on the microbial species that may partake in stomach cancer pathogenesis. However, a random selection of sequenced reads reveals poor percent identities (79 to 94%) of the microbial identification obtained in a BLAST search. This surprising result suggests possible stomach acid induced degradation or modification of the sequenced read that reduced the effectiveness of the metagenomics approach in microbial identification. Further analysis of the dataset highlights that poor percent identities did not arise due to highly fragmented nature of the genetic material where there is a good abundance of sequenced reads in the 100 to 1300 base pair category. More intriguingly, attempts to obtain a correlation between percent identity and read length did not reveal a correlation which meant that stomach acid did not modify all types of nucleotides. More likely, stomach acid only modified low abundance nucleotide in this case, which point to the probability of identifying a microbe in the modified gene fragment in totally unpredictable ways. Overall, data reported in this work suggests caution in the interpretation of results of shotgun metagenomics studies of stomach cancer microbiota where stomach acid likely degraded the genetic material of microbes that may result in mis-identification.
ARTICLE | doi:10.20944/preprints202304.0118.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: antimicrobial activity; natural products; microbial metabolites; plant diseases; biological control
Online: 7 April 2023 (07:53:08 CEST)
The rhizosphere is a rich source of actinomycetes which can produce several potential biologically-active secondary metabolites. The principal goals for this research are to extract, purify and characterize the bioactive secondary metabolites produced by three different strains of actinomycetes isolated from the rhizosphere of rosemary, black locust and olive. The plant growth-promoting effect (PGPE) of the studied strains of actinomycetes on Ocimum basilicum L. (basil) and disease-control effect on necrotic stem lesions of “black leg” caused by Fusarium tabacinum on basil, were in silico evaluated. The cell-free culture filtrates from the studied actinomycetes isolates were evaluated in vitro for their antimicrobial activity against some common phytopathogens. The secondary metabolites obtained from the cell-free culture filtrates have been chemically characterized using high‐resolution electrospray ionization of liquid-chromatography/mass-spectrometric detection (ESI-(HR)Orbitrap-MS). Results of in silico trial showed that all studied isolates demonstrated PGPE on basil seedlings improving some Eco-physiological characteristics and reduced the disease incidence of F. tabacinum. The extracted metabolites from the studied actinomycetes demonstrated antimicrobial activity in Petri-plates assay. The chemical analysis revealed the presence of totally 20 different components. This research emphasizes how valuable the examined isolates are for producing bioactive compounds, indicating their putative antimicrobial activity and their potential employment as fungal-biocontrol agents. In particular, the obtained results revealed the possibility of green-synthesis of some important secondary metabolites such as N-Acetyl-L-histidinol, Rhizocticin A and Eponemycin from actinomycetes. The bioactive metabolites may be successively used to develop novel bio-formulations for both crop protection and/or PGPE.
ARTICLE | doi:10.20944/preprints202303.0534.v1
Subject: Biology And Life Sciences, Other Keywords: Aquifer; Groundwater recharge; Groundwater microbial ecology; Snowmelt; Bacterial communities Perturbation
Online: 31 March 2023 (02:25:18 CEST)
Events of groundwater recharge are associated with changes in the composition of aquifer microbial communities but also abiotic conditions. Modification in the structure of the community can be the result of different environmental condition favoring or hindering certain taxa or due to the introduction of surface-derived taxa. Yet, in both cases, the local hydrogeochemical settings of the aquifer is likely to affect the amount of variation observed. Therefore, in our study, we used 16S rRNA gene sequencing to assess how microbial communities change in response to snowmelt and the potential connectivity between subsurface and surface microbiome in two distinct aquifers located in the region of Vaudreuil-Soulange (Québec, Canada). At both sites, we observed an increase in groundwater level and decrease in temperature following the onset of snow melt in March 2019. Bacterial community composition of each aquifer was significantly different (p < 0.05) between samples collected prior and after groundwater recharge. Furthermore, microbial source tracking results suggested low contribution of surface environments to groundwater microbiome except for months associated with recharge (March 2019 and April 2019). Overall, despite differences in soil permeability between both sites, the period of snow melt was followed by important changes in the composition of microbial communities from aquifers.
ARTICLE | doi:10.20944/preprints202209.0065.v1
Subject: Biology And Life Sciences, Ecology, Evolution, Behavior And Systematics Keywords: Antarctica; microbial communities; refugia; metabarcoding; McMurdo Dry Valleys; soil biodiversity
Online: 5 September 2022 (13:39:20 CEST)
In the cold deserts of the McMurdo Dry Valleys (MDV) the suitability of soil for microbial life is determined by both contemporary processes and legacy effects. Climatic changes and accompanying glacial activity have caused local extinctions and geochemical changes to soil ecosystems over several million years, while high elevation refugia may have escaped these disturbances and existed under relatively stable conditions. This study describes the impact of historical glacial and lacustrine disturbance events on microbial communities across the MDV. Soil bacterial communities from 17 sites representing either putative refugia or sites disturbed during the Last Glacial Maximum (LGM) (22-17kya) were characterized using 16S metabarcoding. Regardless of geographic distance, several putative refugia sites at elevations above 600 meter displayed highly similar microbial communities. At a regional scale, community composition was found to be influenced by elevation and geographic proximity more so than soil geochemical properties. These results suggest that despite the extreme conditions, diverse microbial communities exist in these putative refugia that have presumably remained undisturbed at least through the last glacial maximum. We suggest that similarities in microbial communities can be interpreted as evidence for historical climate legacies on an ecosystem-wide scale.
ARTICLE | doi:10.20944/preprints202207.0113.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: microbial communities; plant-microbe interractions; rhizodeposition; SEED subsystem; shotgun metagenomics
Online: 7 July 2022 (06:05:13 CEST)
The plant microbiome is involved in enhancing nutrient acquisition, plant growth, stress tolerance and reduces chemical inputs. The identification of microbial functional diversity offers the chance to comprehend and engineer them for various agricultural processes. Using a shotgun metagenomics technique, this study examined the functional diversity and metabolic potentials of microbial communities in the rhizosphere soybean. 18 genera were selected out of which six are prominent in sample AB, the prominent genera are Geobacter, Nitrobacter, Burkholderia, Candidatus, Bradyrhizobium and Streptomyces. Twenty-one functional categories were present with 14 of the functions being dominant. The dominant functions include carbohydrates, fatty acids, lipids and isoprenoids, amino acids and derivatives, sulfur metabolism, and nitrogen metabolism. Kruskal- Wallis test was used to test samples’ diversity differences. There was a significant difference in the diversity with p-value of 0.04. ANOSIM was used to analyse the similarities of the samples, p-values and R-values of the samples were 0.01 and 0.5835 respectively. Phosphorus with p-value of0.718 and 64.3% contribution was more prominent among the soil properties that have influence on functional diversity of the samples. Given the functional groups reported in this study, it is clear that soil characteristics had an impact on on the functions role of the rhizospheric microbiome of soybean
ARTICLE | doi:10.20944/preprints202205.0250.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: beach; coastal sand; fecal contamination; FIB; microbial source tracking (MST)
Online: 19 May 2022 (04:18:30 CEST)
Beach sand may act as a reservoir for numerous micro-organisms, including enteric pathogens. Several of these pathogens originate in human or animal feces, which may pose a public health risk. In August 2019, high levels of fecal indicator bacteria (FIB) were detected in the sand of the Azorean beach Prainha, Terceira Island, Portugal. Remediation measures were promptly implemented, including sand removal and the spraying of chlorine to restore the beach sand quality. To determine the biological source of the contamination, during the first campaign, supratidal sand samples were collected from several sites along the beach, followed by microbial source tracking (MST) analyses of Bacteroides markers for five animal species, including humans. Some of the sampling sites revealed the presence of marker genes from dogs, seagulls, and ruminants. Making use of the information on biological sources originating partially from dogs, the municipality enforced restrictive measures for dog-walking at the beach. Subsequent sampling campaigns detected low FIB contamination due to the mitigation and remediation measures that were undertaken, thereby no longer requiring MST marker-gene analysis. This is the first case study where the MST approach was used to determine the contamination sources in the supratidal sand of a coastal beach. Our results show that MST can be an essential approach to determine sources of fecal contamination in the sand. This study shows the importance of holistic management of beaches that should go beyond water quality monitoring for FIB, putting forth evidence for the need for sands also to be monitored.
ARTICLE | doi:10.20944/preprints202203.0405.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: α-amylase inhibitors; diabetes; hemi-pyocyanin; marine discards; microbial conversion
Online: 31 March 2022 (10:47:24 CEST)
α-amylase inhibitors (aAIs) have been proved efficient for the management of type 2 diabetes. This study aimed to search the potential aAIs produced by microbial fermentation. Among various bacterial strains, Pseudomonas aeruginosa TUN03 was found as a potential aAI - producing strain, and shrimp heads powder (SHP) was screened as the most suitable C/N source for fermentation. P. aeruginosa TUN03 exhibited the highest aAIs productivity (3100 U/mL) in the medium containing 1.5% SHP with the initial pH of 7-7.5, and fermentation was performed at 27.5 °C in 2 days. Further, aAIs compounds were investigated for scale-up production in a 14 L – bioreactor system, and the results highlighted high yield (4200 U/mL) in much shorter fermentation time (12 h) compared to fermentation in flasks. The bioactivity-guided purification resulted in the isolation of one major target compound. This active compound was confirmed as hemi-pyocyanin (HPC), with good purity, via using high-performance liquid chromatography and gas chromatography-mass spectrometry. Notably, HPC demonstrated potent activity comparable to acarbose, a commercial antidiabetic drug; this is the first-ever report of aAI activity of HPC. The docking study indicated that HPC inhibits α-amylase via binding to amino acid Arg421 at the biding site on enzyme α-amylase with good binding energy (-9.3 kcal/mol) and creating two linkages of H-acceptor.
ARTICLE | doi:10.20944/preprints202112.0388.v2
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: Mollisol; soil organic matter; microorganisms; microbial index; crop growing season
Online: 21 February 2022 (12:05:40 CET)
Tillage has been reported to induce seasonal changes of organic carbon (Сmicro) and nitrogen (Nmicro) in biomass of microorganisms. Soil microorganisms execute such ecosystem functions as: it is an immediate sink of labile biophil elements; it is an agent of a conversion, catalysis and synthesis of humus substances; it transforms soil contaminants into non-hazardous wastes; it participates in soil aggregation and pedogenesis as a whole. However, the seasonal turnover of microorganisms on arable lands in temperate ecosystems has not been investigated on a relevant level. Hence, we aimed to study the dynamics of such soil microbial biomass patterns as: Сmicro, Nmicro, microbial index (MI = (Сmicro/CTOC)·100, %) and CO2-C emission on the background of 9 years of tillage and 22 years of abandoned (Ab) and fallow (F) usage. Our study was conducted on a long-term experimental site on a Mollisol in the northeast China. The maximum Сmicro and Nmicro content was found: at the beginning of the growing season – in 0-10-; in mid-July – in 20-40 cm layers, while the minimum – in August-October. The Сmicro content ranged from 577.79- and 381.79 mg-1 kg-1 under Ab in spring to 229.53- and 272.86 mg-1 kg-1 in autumn under CT (conventional tillage) and F in 0-10- and 10-20 cm layers, respectively. The amplitude of Nmicro content changes was several times lower comparatively to Сmicro. The smallest quartile range (IQR0.25-0.75) of such changes was under: no-till (NT) and Ab in 0-10-, NT and F – in 10-20- and CT - in 20-40 cm layers. The widest Сmicro : Nmicro ratio was found at F and CT – in 0-20- and CT and rotational tillage (Rot) – in 20-40 cm layers. MI dynamics resembled the trends of Сmicro and Nmicro and changed from 0.72 0.168- tо 2.00 0,030 %. The highest part of Сmicro in CTOC was at Ab (1.82 1.85 %) and NT (1.66 1.52 %) – in 0-10-; Ab (1.23 1.27 %) and NT (1.29 1.32 %) – in 10-20- and – Ab (1.19 1.09 %) and F (1.11 1.077 %) – in 20-40 cm layers, correspondingly. The Pearson’s correlation coefficient between Сmicro and CTOC increased from the upper 0-10- to the lower 20-40 cm layer, it was "strong" and "high" between Сmicro and CTOC. Different use of Mollisol affected the amplitude of Сmicro and Nmicro seasonal changes, but it didn’t change their trend. Our results suggest the key role of Ab and NT technologies in Сmicro accumulation in total organic carbon (TOC).
ARTICLE | doi:10.20944/preprints202201.0375.v1
Subject: Biology And Life Sciences, Ecology, Evolution, Behavior And Systematics Keywords: multi-pond saltern; salinity gradients; microbial community; assembly; ecological processes
Online: 25 January 2022 (09:58:30 CET)
Salinity acts as a critical environmental filter on microbial communities in natural systems, negatively affecting microbial diversity. However, how salinity affects the community assembly remains unclear. This study used Wendeng multi-pond saltern as a model to evaluate the prokaryotic community composition and diversity and quantify the relative importance of ecological processes across salinity gradients. Results showed that low saline salterns (45-80 g/L) exhibited higher bacterial diversity than those in high saline salterns (175-265 g/L). The relative abundance of taxa assigned to Halanaerobiaceae, Haloferacaceae, Desulfohalobiaceae, Phormidiaceae, Rohodobacteraceae, and Nitrococcaceae was higher with increasing salinity. Salinity and pH were the primary environmental factors that directly or indirectly determined the composition and diversity of prokaryotic communities. Microbial co-occurrence network dynamics were more complex in the sediment than in water of salterns. An infer Community Assembly Mechanisms by Phylogenetic-bin-based null model analysis (iCAMP) showed that microbial community assembly in sediment and water differed. Our findings provide more information about microbial community structure and the importance of various ecological processes in controlling microbial community diversity and succession along salinity gradients in water and sediment environments.
ARTICLE | doi:10.20944/preprints202112.0173.v1
Subject: Biology And Life Sciences, Biology And Biotechnology Keywords: microbial production; bioethanol; biodiesel; SynB; food security; information science; scientometry.
Online: 10 December 2021 (12:11:21 CET)
Despite the acknowledged relevance of renewable energy sources, biofuel production supported by food-related agriculture has faced severe criticism. One way to minimize the considered negative impacts is the use of sources of non-food biomass or wastes. Synthetic biology (SB) embraces a promising complex of technologies for biofuel production from non-edible and sustainable raw materials. Therefore, it is pertinent to identify the global evolution of investments, concepts, and techniques underlying the field in support of policy formulations for sustainable bioenergy production. We mapped the SB scientific knowledge related to biofuels using software that combines information visualization methods, bibliometrics, and data mining algorithms. The United States and China have been the leading countries in developing SB technologies. Technical University of Denmark and Tsinghua University are the institutions with higher centrality and have played prominent roles besides UC-Los Angeles and Delft University Technology. We identified six knowledge clusters under the terms: versatile sugar dehydrogenase, redox balance principle, sesquiterpene production, Saccharomyces cerevisiae, recombinant xylose-fermenting strain, and Clostridium saccharoperbutylacetonicum N1-4. The emerging trends refer to specific microorganisms, processes, and products. Yarrowia lipolytica, Oleaginous yeast, E. coli, Klebsiella pneumoniae, Phaeodactylum tricornutum, and Microalgae are the most prominent microorganisms, mainly from the year 2016 onwards. Anaerobic digestion, synthetic promoters, and genetic analysis appear as the most relevant platforms of new processes. Improved biofuels, bioethanol, and N-butanol are at the frontier of the development of SB-derived products. Synthetic biology is a dynamic interdisciplinary field in environmentally friendly bioenergy production pushed by growing social concerns and the emergent bioeconomy.
ARTICLE | doi:10.20944/preprints202110.0284.v1
Subject: Biology And Life Sciences, Ecology, Evolution, Behavior And Systematics Keywords: Watershed; biogeographic patterns; microbial biogeography; biodiversity; spatial distribution; research unit
Online: 20 October 2021 (09:34:27 CEST)
Biogeography research is flawed by the poor understanding of microbial distributions due to the lack of a systematic research framework, especially regarding appropriate study units. By combining pure culture and molecular methods, we studied the biogeographic patterns of nematode-trapping fungi by collecting and analysing 2,250 specimens from 228 sites in Yunnan Province, China. We found typical watershed patterns at the species and genetic levels of nematode-trapping fungi. The results showed that microbial biogeography could be better understood by 1) using watersheds as research units, 2) removing the coverup of widespread species, and 3) applying good sampling efforts and strategies. We suggest that watersheds could help unify the understanding of the biogeographic patterns of animals, plants, and microbes and may also help account for the historical and contemporary factors driving species distributions.
REVIEW | doi:10.20944/preprints202107.0273.v1
Subject: Biology And Life Sciences, Anatomy And Physiology Keywords: Plastisphere; Plastic biofilms; Microbial communities; Marine plastic pollution; Plastic biodegradation
Online: 12 July 2021 (22:12:28 CEST)
The microbial colonisers of plastics – the ‘plastisphere’ – can affect all interactions that plastics have with their surrounding environments. While only specifically characterised within the last 10 years, at the beginning of 2021 there were 140 primary research and 65 review articles that investigate at least one aspect of the plastisphere. We gathered information on the locations and methodologies used by each of the primary research articles, highlighting several aspects of plastisphere research that remain understudied: (i) the non-bacterial plastisphere constituents; (ii) the mechanisms used to degrade plastics by marine isolates or communities; (iii) the capacity for plastisphere members to be pathogenic or carry antimicrobial resistance genes; and (iv) meta-OMIC characterisations of the plastisphere. We have also summarised the topics covered by the existing plastisphere review articles, identifying areas that have received less attention to date – most of which are in line with the areas that have fewer primary research articles. Therefore, in addition to providing an overview of some fundamental topics such as biodegradation and community assembly, we discuss the importance of eukaryotes in shaping the plastisphere, potential pathogens carried by plastics and the impact of the plastisphere on plastic transport and biogeochemical cycling. Finally, we summarise the future directions suggested by the reviews that we have evaluated and suggest other key research questions.
REVIEW | doi:10.20944/preprints202105.0572.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: microalgae; marine bacteria; quorum sensing signals; alkyl quinolones; microbial loop
Online: 24 May 2021 (13:34:11 CEST)
Quorum sensing (QS) describes a process by which bacteria can sense the local cell density of their own species, thus enabling them to coordinate gene expression and physiological processes on a community-wide scale. Small molecules called autoinducers or QS signals, which act as intraspecies signals, mediate quorum sensing. As our knowledge of QS has progressed, so too has our understanding of the structural diversity of QS signals, along with the diversity of bacteria conducting QS and the range of ecosystems in which QS takes place. It is now also clear that QS signals are more than just intraspecies signals. QS signals mediate interactions between species of prokaryotes, and between prokaryotes and eukaryotes. In recent years, our understanding of QS signals as mediators of algae–bacteria interactions has advanced such that we are beginning to develop a mechanistic understanding of their effects. This review will summarize the recent efforts to understand how different classes of QS signals contribute to the interactions between planktonic microalgae and bacteria in our oceans, primarily N-acyl-homoserine lactones, their degradation products tetramic acids, and 2-alkyl-4-quinolones. In particular, this review will discuss the ways in which QS signals alter microalgae growth and metabolism, namely as direct effectors of photosynthesis, regulators of the cell cycle, and as modulators of other algicidal mechanisms. Furthermore, the contribution of QS signals to nutrient acquisition is discussed, and finally how microalgae can modulate these small molecules to dampen their effects.
ARTICLE | doi:10.20944/preprints202011.0674.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: chitosan; microbial synthesis; milk composition; volatile fatty acids; purine derivatives
Online: 26 November 2020 (14:15:52 CET)
The study compared the influence of chitosan sources on rumen fermentation, methane emission and milk production in lactating dairy cows fed a glycerin-based diet. Six, lactating Holstein-Frisian crossbreeds (410 ± 5.0 kg BW, 120 ± 21 day-in-milk), were arranged in a 3 x 3 replicated Latin square design. In addition to control, a 2% chitosan extract supplement and a 2% commercial chitosan supplement of dry matter intake were the treatments. The results denoted that no significant differences on daily dry matter, nutrients or estimated energy intake were noted when cows received different sources of chitosan. Nutrient digestibility was not influenced differently by extraction based or commercial chitosan supplements. The pH, temperature, ammonia nitrogen, blood urea and microbial count were similar among treatments. The different sources of chitosan supplements did not change the totals of volatile fatty acids, acetate and butyrate; in contrast, different chitosan sources influenced (P<0.05) propionate content. The ruminal acetate to propionate ratio was markedly (P<0.05) reduced with chitosan supplement, but no change appeared between sources of chitosan. At 4 hours after feeding, the methane estimation signiﬁcantly decreased with the addition of chitosan supplementation (P<0.05) compared to the control group. The purine derivatives and microbial protein synthesis were not altered by the treatments. No significant differences existed on milk yield, milk composition or milk urea nitrogen when cows received different sources of chitosan (P>0.05). In sum, supplementing extracted chitosan showed more potential than did commercial chitosan for enhancing economic efficiency and recycling shrimp residues, therefore, reducing environmental waste.
ARTICLE | doi:10.20944/preprints202002.0433.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: microbiome; water stress; adaptation; function prediction; microbial network topology; extremophiles
Online: 28 February 2020 (12:34:35 CET)
Over the past 150 million years, the hyperarid core of the Atacama Desert has been transformed by geologic and atmospheric conditions into one of the most unique and inhospitable landscapes on the planet. This makes it an ideal Mars analog that has been explored for decades as preliminary studies on the space life discovery. However, two heavy rainfalls that occurred in the Atacama in 2015 and 2017 provide a unique opportunity to study the response of resident extremophiles to rapid environmental change associated with excessive water and salt shock. Here we combine geochemical analyses with molecular biology to study the variations in salts and microbial communities along an aridity gradient, and to examine the reshuffling of hyperarid microbiomes before and after the two rainfall events. Analysis of microbial community composition revealed that soils within the southern desert were consistently dominated by Actinobacteria, Proteobacteria, Acidobacteria, Planctomycetes, Chloroflexi, Bacteroidetes, Gemmatimonadetes, and Verrucomicrobia; soils within the hyperarid sites were dominated by Aquificae and Deinococcus-Thermus before heavy rainfalls, while these organisms almost totally diminished after rainfall, and the hyperarid microbial consortia and metabolisms transformed to a more southern desert pattern along with increased biodiversity. Salts at the shallow subsurface were dissolved and leached down to a deeper layer, both benefitting and challenging indigenous microorganisms with the excessive input of water and ions. Microbial viability was found to change with aridity and rainfall events but correlated with elevation, pH, conductivity, chloride, nitrate, sulfate, and soil organic matters (SOM). Metagenomic functional pathways related to stressor responses also increased in post-rainfall hyperarid soils. Our findings contribute to the primary goal of Atacama Mars analog research for understanding the microbial community structure and adaptations: this study sheds light on the structure of xerophilic, halophilic, and radioresistant microbiomes in hyperarid environments, and their response to changes in water availability.
ARTICLE | doi:10.20944/preprints201906.0272.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: microbial interactions; cross-feeding; synthetic communities; volatolomic; biofilm; alcoholic fermentation
Online: 26 June 2019 (15:51:06 CEST)
used traditional microbial starters revealed that effective fermentation requires three microbial strains with complementary metabolic activities: filamentous fungi (Rhizopus oryzae), yeast (Saccharomyces cerevisiae), and lactic acid bacteria (Lactobacillus plantarum). Relative to natural communities, modulation of the ratio of these three microorganisms led to significant differences not only in terms of ethanol and organic acid production, but also with the profile of volatile compounds. However, inoculation of an equal ratio of spores/cells of the three aforementioned microbial strains led to a flavor profile and ethanol yield similar to that obtained with natural communities. Compartmentalization of metabolic tasks through the use of a biofilm cultivation device allowed further improvement of the entire fermentation process, notably by increasing the amount of key components of the aroma profile of the fermented beverage (i.e., mainly phenylethyl alcohol, isobutyl alcohol, isoamyl alcohol, and 2-methyl-butanol) and reducing the amount of off-flavor compound. This study represents an initial step toward understanding interkingdom microbial interactions with a strong potential for application in the food biotechnology.
ARTICLE | doi:10.20944/preprints201808.0082.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: mine waste; lead; zinc; cadmium; microbial role; sulfur-reducing bacteria
Online: 4 August 2018 (11:07:24 CEST)
Milling and mining metal ores are major sources of heavy metal contamination. The Spring River and its tributaries in southeast Kansas are contaminated with Pb, Zn, and Cd as a result of 120 years of mining activities. Trace metal transformations and cycling in mine waste materials greatly influence their mobility and toxicity and affect plant productivity and human health. It has been hypothesized that under reduced conditions in sulfate-rich environments, these metals can be transformed into their sulfide forms, thus limiting mobility and toxicity. We studied biogeochemical transformations of Pb, Zn and Cd in flooded subsurface mine waste materials, natural or treated with organic carbon (OC) and/or sulfur (S), by combining advanced microbiological and X-ray spectroscopic techniques to determine the effects of treatments on the microbial community structure and identify the dominant functional genes involved in the biogeochemical transformations, especially metal sulfide formation over time. Samples collected from medium-, and long-term submerged columns were used for microarray analysis via functional gene array (GeoChip 4.2). The total number of detected gene abundance decreased under long-term submergence, but major functional genes abundance was enhanced with OC plus S treatment. The microbial community exhibited a substantial change in structure in response to OC and S addition. Sulfur-reducing bacteria genes dsrA/B were identified as key players in metal sulfide formation via dissimilatory sulfate reduction. Uniqueness of this study is that microbial analyses presented here in details are in agreements with molecular-scale synchrotron-based X-ray data supporting that OC-plus-S treatment would be a promising strategy for reducing metal toxicity in mine waste materials.
REVIEW | doi:10.20944/preprints201807.0016.v3
Subject: Biology And Life Sciences, Biophysics Keywords: bioresorbable implants; corrosion layer; vascular stents; orthopedic implants; microbial infections
Online: 11 July 2018 (13:54:04 CEST)
Medical implants made of biodegradable materials could be of advantage for temporary applications such mechanical support during bone-healing or as vascular stents to keep blood vessels open. After completion of the healing process the implant would disappear, avoiding long-term side effects or the need for surgical removal. Various corrodible metal alloys based on magnesium, iron or zinc have been proposed as sturdier and potentially less inflammatory alternative to degradable organic polymers, in particular for load-bearing applications. Despite the recent introduction of magnesium-based screws the remaining hurdles to routine clinical applications are still challenging, such as limiting mechanical material characteristics or unsuitable corrosion characteristics. Here, salient features and clinical prospects of currently investigated biodegradable implant materials are summarized with a main focus on magnesium alloys. A mechanism of action for the stimulation of bone growth due to the exertion of mechanical force by magnesium corrosion products is discussed. To explain divergent in vitro and in vivo effects of magnesium a novel model for bacterial biofilm infections is proposed which predicts crucial consequences antibacterial implant strategies.
ARTICLE | doi:10.20944/preprints202311.1849.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: antioxidant activity; biotechnology; functional groups; hydrolysate; microbial population; molecular weight; gelatin
Online: 29 November 2023 (11:01:37 CET)
Chicken collagen is a promising raw material source to produce gelatins and hydrolysates. Gelatins and hydrolysates can be prepared biotechnologically using proteolytic enzymes produced by submerged fermentation of genetically modified microorganisms. By choosing the appropriate process conditions, such changes can be achieved at the molecular level of collagen, making it possible to prepare products with targeted properties for advanced cosmetic, pharmaceutical, medical or food applications. The research aims to investigate: i) antioxidant activity (DPPH and ABTS) in model samples of chicken collagen products (gelatin and hydrolysates); ii) distribution of molecular weights by the GPC-RID analysis method; iii) functional groups and configuration of polypeptide chains related to molecular level properties using FTIR; iv) the microbiological properties on SDA, PCA, TSA and VRBL microbial populations using MALDI method. Antioxidant activity towards ABTS radicals of more than 80% was found for all samples. The molecular weights of all gelatin samples showed typical α- and β-chains. FTIR analysis confirmed that the samples showed all typical vibrational regions for collagen cleavage products, Amide A and B, Amide I, II, and III at characteristic values. Microbiological analysis of the prepared samples showed no undesirable bacteria that would limit advanced applications of the prepared products. Gelatins and hydrolysates from chicken stomachs represent a promising alternative to products made from standard collagen tissues of terrestrial animals.
REVIEW | doi:10.20944/preprints202310.1556.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: Methanogens; enteric methane emission; cattle; microbiome; holistic; extra-intestinal microbial communities
Online: 25 October 2023 (05:29:38 CEST)
Despite the extensive research conducted on ruminal methanogens and anti-methanogenic intervention strategies over the last 50 years, most of the currently researched enteric CH4 abatement approaches have shown limited efficacy. This is largely because of the complex nature of animal production and the ruminal environment, host genetic variability of CH4 production, and an incomplete understanding of the role of the ruminal microbiome in enteric CH4 emissions. Recent sequencing-based studies suggest the presence of methanogenic archaea in extra-gastrointestinal tract tissues, including respiratory and reproductive tracts of cattle. While these sequencing data require further verification by culture-dependent methods, the consistent identification of methanogens with relatively greater frequency in the airway and urogenital tract of cattle plus increasing appreciation of the microbiome-gut-organ axis highlight the potential interactions between ruminal and extra-gastrointestinal methanogenic communities. Thus, a traditional singular focus on ruminal methanogens may not be sufficient, and a holistic approach which takes into consideration of the transfer of methanogens between ruminal, extra-gastrointestinal, and environmental microbial communities is of necessity to develop more efficient and long-term ruminal CH4 mitigation strategies. In the present review, we provide a holistic survey of the methanogenic archaea present in different anatomical sites of cattle and discuss potential seeding sources of the ruminal methanogens.
ARTICLE | doi:10.20944/preprints202310.0457.v1
Subject: Physical Sciences, Applied Physics Keywords: microbial fuel cells; energy recovery; biosensors; bio-electrochemical sensors; Antibiotic contamination
Online: 9 October 2023 (04:34:31 CEST)
This work demonstrates that microbial fuel cells (MFCs), optimized for energy recovery, can be used as an effective tool to detect the presence of antibiotics in water-based environments. MFCs directly convert chemical energy of organic matter in electrical energy thanks to electroactive biofilms. The efficiency of the conversion process can be significantly affected by the presence of contaminants acting as toxicants for the biofilm. In the present work, we demonstrate that MFCs can successfully detect the presence of antibiotic residues in water and water-based electrolytes associated to the food industry, especially using honey as a new and more complex electron donor. The effectiveness of MFCs to sense antibiotics is here demonstrated for tetracycline that was added to both water and water/honey electrolytes with a minimum concentration close to 3.5 μg⁄kg. MFCs not only efficiently detect the presence of tetracycline in both the electrolytes, but also recover the same performance after each cycle of exposure, showing to a be very robust and reliable technology for both biosensing and energy recovery.
ARTICLE | doi:10.20944/preprints202310.0199.v1
Subject: Biology And Life Sciences, Ecology, Evolution, Behavior And Systematics Keywords: amplicon-based metagenomics; Maritime Antarctica; microbial domains antagonism; Archaea; Fungi; Bacteria
Online: 5 October 2023 (14:35:52 CEST)
Within an amplicon-based metagenomic study of Archaea, Fungi, and Bacteria in Livingston Island, Maritime Antarctica, in many of the samples antagonisms between these three super kingdoms were observed under the form of an inversely proportional dependence of the richnesses of the three types of microorganisms. This was quantified - based on the observed numbers of the total tags and the numbers of the operational taxonomic units (OTUs), as well as based on four alpha diversity parameters – the Shannon, the Simpson, the Chao1, and the ACE indices. We found that the most discriminative results in the antagonism measuring were observed in the comparison of the numbers of the OTUs and the ACE community richness estimator. The antagonism between Archaea and Fungi was strongest, followed by that of Archaea and Bacteria. The Fungi-Bacteria antagonism was slightly detectable. Pearson and Spearman correlation analysis also showed a statistically significant negative correlation between the fungal and archaeal effective tags, while the correlation between archaeal and bacterial diversity was positive. Indications of the order of primary microbial succession in barren ecological niches were also observed, demonstrating that Archaea and Bacteria are the pioneers, followed by Fungi which in time would displace Archaea.
ARTICLE | doi:10.20944/preprints202306.1722.v1
Subject: Chemistry And Materials Science, Ceramics And Composites Keywords: Zirconia; CAD/CAM; ultrasonic scaling; SEM; surface micro topography; microbial biofilm;
Online: 25 June 2023 (07:13:11 CEST)
Objective: The purpose of this study was to evaluate the surface texture and biofilm adhesion of veneered or CAD/CAM milled zirconia (partially stabilized with yttrium) after professional oral hygiene procedures. Samples (4x4 mm, thickness 2 mm; n = 72) were separated from zirconia blanks (3Y-TZP-LA). One group was veenired with ceramics and the other group of samples was CAD/CAM milled. Each group had 2 subgroups: polished and glazed. The samples were subjected to simulated strokes of professional brushing using abrasive paste and ultrasonic scaling. Parameters of surface micromorphology and receptivity to biofilm were calculated before and after simulating the given methods of professional maintenance of oral hygiene. The characteristics of zirconia surface were evaluated by scanning electron microscopy (SEM). Microbial bacterial/fungal species (Staphylococcus aureus, Streptococcus sanguinis and Candida albicans) were used and cultured on the respective sterilized zirconia surfaces. The amount of biofilm formation on zirconia surface was quantified by colony forming unit (CFU) counts. Results: SEM analysis showed the greatest change in surface microtopography after the use of ultrasonic scaling, in glazed zirconia samples. Less formation of colonies on the surface CAD/CAM milled zirconia restorations was observed. Conclusion: Routine methods of professional maintenance of oral hygiene can damage the surface of glazed zirconia restorations.
ARTICLE | doi:10.20944/preprints202304.1136.v1
Subject: Environmental And Earth Sciences, Ecology Keywords: Bacterial communities; Fungal communities; Mineral-solubilizing microbial inoculums; Robinia pseudoacacia L.
Online: 28 April 2023 (07:29:24 CEST)
The addition of mineral-solubilizing microbial inoculums is a kind of biological measure for vegetation restoration of rock mining areas. Its function is to accelerate soil weathering, improve soil fertility, improve the ability of plants to fix soil. Through understanding the response of plant rhizosphere microbial community to the mineral-solubilizing microbial inoculums, it is helpful to popularize the use of mineral-solubilizing microbial inoculums. However, little is known about the changes of plant rhizosphere soil microbial communities after the addition of mineral-solubilizing microbial inoculums. Therefore, the purpose of this study was to reveal the pasthways through which different mineral-solubilizing microbial inoculums positively affect underground part of R. pseudoacacia. A pot experiment was conducted to investigate the responses of rhizosphere soil bacterial and fungal communities in R. pseudoacacia by taking 32 samples from four different mineral-solubilizing microbial inoculums treatments. The results showed that the effect of mineral-solubilizing microbial inoculums on the structure of fungal community was greater than that of bacterial community. But the relative abundance of Proteobacteria was increased, which had a strong positive correlation with root nodulation. In terms of microbial diversity, mineral-solubilizing microbial inoculums had a greater effect on the diversity and evenness of bacterial community. It is worth noting that correlation analysis showed that Proteobacteria and Verrucomicrobia in bacteria and Ascomycota and Zoopagomycota in fungi were positively correlated with soil enzyme activity and plant growth. RDA analysis showed that the relative abundance of these two phyla in bacteria also had positive effects on plant root nodulation. Our results showed that the addition of mineral-solubilizing microbial inoculums can optimize the rhizosphere soil microbial community structure, promote R. pseudoacacia root nodulation, and enhance the nitrogen fixation capacity of plants. In addition, this study can provide a theoretical basis for the application of mineral-solubilizing microbial inoculums to a wide range of slope ecological restoration.
ARTICLE | doi:10.20944/preprints202304.0871.v1
Subject: Environmental And Earth Sciences, Soil Science Keywords: Fungicide; inoculant; insecticide; microbial enhancer; soil activator; soil conditioner; soil stimulant
Online: 25 April 2023 (03:26:11 CEST)
Field studies were conducted in 2016, 2017, and 2020 in south-central and the Coastal Bend regions of Texas to determine the effects of various biostimulants and soil additives on corn growth and yield. In south-central Texas, the use of pop-up fertilizer (9-30-0 + Zn) either alone or in combination with either 2% N, bifenthrin, or bifenthrin + pyraclostrobin resulted in the greatest corn vigor but a yield response was only noted with pop-up fertilizer alone at 28062 or 46771 ml ha-1 in one year. In the Coastal Bend region, leaf tissue analysis showed that only Fe was affected with the use of any soil additive. Bacillus licheniformis + bacillus megaterium + bacillus pumilus increased Fe leaf tissue content by 20% over the untreated check. Radicoat seed coating at 438 ml ha-1 reduced corn plant stand by 10% and Pseudomonas brassicaceanum reduced corn height when compared with the untreated check; however, no differences in test weight or yield from the untreated check were noted with any soil additive. Little if any impacts of the use of biostimulants or soil amendments were seen in these studies.
ARTICLE | doi:10.20944/preprints202205.0410.v1
Subject: Environmental And Earth Sciences, Soil Science Keywords: mugwort; perennial cropping; conventional rotations; sustainable agri-culture; soil microbial community
Online: 31 May 2022 (05:20:06 CEST)
Perennial cropping play vital roles in regulating soil carbon sequestration and thus mitigating climate change. However, how perennial cropping affects soil microbial community remains elusive. Using a field investigation, this study was conducted to examine the effects of mugwort cropping along a chronosequence (that is, wheat-maize rotation, 3-year, 6-year, and 20-year mugwort cropping) on soil microbial community in temperate regions of Northern China. The results showed that the highest total, actinomycetes, and fungi PLFAs were found in the 3-year mugwort cropping soils. All PLFAs of microbial groups were lowest in the 20-year mugwort cropping soils. All of the three cropping years of mugwort increased network complexity of soil microbial community. Changes in total nitrogen and phosphorus content as well as the ratio of ammonium nitrogen to nitrate nitrogen could be primarily explain the variations in soil microbial community along the mugwort cropping chronosequence. Our observations highlight the contrasting impacts of soil microbial community to short-term and long-term mugwort cropping compared to conventional rotations and would have critical implications for sustainable agricultural management under perennial cropping in temperate regions.
ARTICLE | doi:10.20944/preprints202106.0434.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: bacterial community composition; metabolic activity; microbial diversity; soil erosion; soil quality
Online: 16 June 2021 (10:23:06 CEST)
Among the agricultural practices promoted by the Common Agricultural Policy to increase soil functions, the use of cover crops is a recommended tool to improve the sustainability of Mediter-ranean woody crops such as olive orchards. However, there is a broad range of cover crop ty-pologies in relation to its implementation, control and species composition. In that sense, the in-fluence of different plant species on soil quality indicators in olive orchards remains unknown yet. This study describes the effects of four treatments based on the implementation of different ground covers (CC-NAT, CC-GRA and CC-MIX) and conventional tillage (TILL) on soil erosion, soil physicochemical and biological properties, and soil microbial communities after 8 years of cover crop establishment. Our results have demonstrated that the presence of a temporary cover crop (CC), compared to a soil under tillage (TILL), can reduce soil losses and maintain good soil physicochemical properties and modify greatly the structure and diversity of soil bacterial com-munities and its functioning. The presence of a homogeneous CC of gramineous (Lolium rigidum or Lolilum multiflorum) (CC-GR) for 8 years significantly increased the functional properties of the soil as compared to TILL; although the most significant change was a modification on the bacte-rial community composition that was clearly different from the rest of treatments. On the other hand, the use of a mixture of plant species (CC-MIX) as a CC for only two years although did not modify greatly the structure and diversity of soil bacterial communities compared to the TILL soil, induced significant changes on the functional properties of the soil, and reverted those properties to a level similar to that of an undisturbed soil that had maintained a natural cover of spontaneous vegetation for decades (CC-NAT).
Subject: Environmental And Earth Sciences, Geophysics And Geology Keywords: travertine; terrestrial thermal springs; Central Italy; microbial mats; EPS-mediated mineralization
Online: 30 July 2020 (10:55:30 CEST)
The study of hydrothermal travertines contributes to the understanding of the interaction between physico-chemical processes and the role played by microbial mats and biofilms in influencing carbonate precipitation. Three active travertine sites were investigated in Central Italy to identify the types of carbonate precipitates and the associated microbial mats at varying physico-chemical parameters. Carbonate precipitated fabrics at the decimetre- to millimetre-scale and microbial mats vary with decreasing water temperature: a) at high temperature (55-44°C) calcite or aragonite crystals precipitate on microbial mats of sulphide oxidizing, sulphate reducing and anoxygenic phototrophic bacteria forming filamentous streamer fabrics, b) at intermediate temperature (44-40°C), rafts, coated gas bubbles and dendrites are associated with Spirulina cyanobacteria and other filamentous and rod-shaped cyanobacteria, c) low temperature (34-33°C) laminated crusts and oncoids in a terraced slope system are associated with diverse Oscillatoriales and Nostocales filamentous cyanobacteria, sparse Spirulina and diatoms. At the microscale, carbonate precipitates are similar in the three sites consisting of prismatic calcite (40-100 µm long, 20-40 µm wide) or acicular aragonite crystals organized in radial spherulites, overlying or embedded within biofilm EPS (Extracellular Polymeric Substances). Microsparite and sparite crystal size decreases with decreasing temperature and clotted peloidal micrite dominates at temperatures < 40°C, also encrusting filamentous microbes. Carbonates are associated with gypsum and Ca-phosphate crystals; EPS elemental composition is enriched in Si, Al, Mg, Ca, P, S and authigenic aluminium-silicates form aggregates on EPS. This study confirms that microbial communities in hydrothermal travertine settings vary as a function of temperature. Carbonate precipitate types at the microscale do not vary considerably, despite different microbial communities suggesting that travertine precipitation, driven by CO2 degassing, is influenced by biofilm EPS acting as template for crystal nucleation (EPS-mediated mineralization) and affecting the fabric types, independently from specific microbial metabolism.