REVIEW | doi:10.20944/preprints202009.0548.v1
Subject: Life Sciences, 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/preprints202209.0065.v1
Subject: Biology, Ecology 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/preprints201906.0053.v1
Subject: Life Sciences, 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/preprints201609.0056.v1
Subject: Biology, Agricultural Sciences & 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.
Subject: Life Sciences, Biochemistry 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.
ARTICLE | doi:10.20944/preprints201709.0016.v1
Subject: Biology, 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/preprints201906.0272.v1
Subject: Life Sciences, 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/preprints202207.0113.v1
Subject: Life Sciences, 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/preprints202007.0668.v1
Subject: Biology, Ecology Keywords: Intestinal microbiome; infant microbiota; diet; westernized; non-westernized; lifestyle; microbial diversity; human health
Online: 28 July 2020 (08:37:38 CEST)
The Human Gut Microbiome is an important host’s component defining its health. These microorganisms are mutualistic symbionts dependent on factors such as host’s age, subsistence models and sociocultural practices, among others. The conjunction of these factors define the microbial ecosystem dynamics. Using a fecal microbiome approach in children, a comparison of two Mexican communities with contrasting lifestyles: “westernized” (Mexico City) and “non-westernized” (Me’phaa indigenous group) was evaluated. The main differences between these two communities are in bacteria associated with different types of diets (high animal protein and refined sugars vs high fiber food, respectively). In addition, the gut microbiome of Me’phaa children showed higher total diversity and the presence of exclusive phyla, such as Deinococcus-Thermus, Chloroflexi, Elusimicrobia, Acidobacteria and Fibrobacteres. In contrast, Mexico City children had less diversity and the exclusive presence of Saccharibacteria phylum which is associated with the degradation of sugar compounds. This comparison allows further exploration of the selective pressures affecting microbial ecosystemic composition over the course of human evolution and the potential consequences of pathophysiological states correlated with westernization lifestyles.
ARTICLE | doi:10.20944/preprints202002.0433.v1
Subject: Earth Sciences, Environmental Sciences 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/preprints201808.0073.v1
Subject: Earth Sciences, Environmental Sciences Keywords: Artificial restoration; ecological restoration; coal mining subsidence; semi–arid; soil microbial community
Online: 3 August 2018 (15:48:23 CEST)
Increased attention has been paid to the influence of coal mining subsidence on ecological environment. Restoration of ecosystem in damaged mining area is critical for restoring disturbed environment. The comparing of plant communities and microbial communities in the artificial restoration and natural restoration areas provides an effective method for evaluating the restoration effects. However, such studies are limited in coal mining subsidence restoration areas. Subsidence area in Shendong mining area, located in the semi-arid region of Western China, was restored from 2003 with 5 ecological restoration plant species. In July 2017, the comparison and analysis of plant and microbial communities were conducted at the artificial restoration areas (AR) and the natural remediation areas (NR). The results showed that the artificial ecological restoration in Shendong mining area has achieved some success, but it has not recovered to a similar ecosystem before the destruction. A higher plant species, coverage and bacterial community diversity were observed in AR. However, these features have lower similarity compared with those in NR sites. Potential soil factors, such as pH, moisture content, total carbon content, organic matter, nitrogen and bulk density, have a greater impact on soil bacterial community structure and diversity. In the ecological restoration of the mining area, attention should be paid to the restoration of soil properties in the mining area. This study can provide theoretical guidance for more scientific ecological restoration in the damaged mining area.
DATA DESCRIPTOR | doi:10.20944/preprints202106.0368.v1
Subject: Life Sciences, Biochemistry 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.
CONCEPT PAPER | doi:10.20944/preprints202107.0546.v1
Subject: Biology, Anatomy & Morphology 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
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.
REVIEW | doi:10.20944/preprints202207.0230.v1
Subject: Biology, Agricultural Sciences & 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.
ARTICLE | doi:10.20944/preprints202203.0353.v1
Subject: Chemistry, Other 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, Anatomy & Morphology 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: Life Sciences, 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, Agricultural Sciences & 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/preprints202105.0332.v1
Subject: Life Sciences, Biochemistry 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.
REVIEW | doi:10.20944/preprints201912.0245.v1
Subject: Biology, Other 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: Life Sciences, 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, Agricultural Sciences & 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
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/preprints202202.0208.v1
Subject: Biology, 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, Agricultural Sciences & 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 & Pharmacology, Gastroenterology 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.
ARTICLE | doi:10.20944/preprints202108.0280.v1
Subject: Life Sciences, 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.
REVIEW | doi:10.20944/preprints202102.0244.v1
Subject: Biology, Anatomy & Morphology 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, Other 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.
SHORT NOTE | doi:10.20944/preprints202111.0374.v1
Subject: Life Sciences, 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, Agricultural Sciences & 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: Life Sciences, Biochemistry 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, Agricultural Sciences & 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, 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/preprints201810.0382.v1
Subject: Biology, Agricultural Sciences & 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: Earth Sciences, Environmental Sciences 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/preprints202205.0250.v1
Subject: Earth Sciences, Environmental Sciences 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, Other 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, Agricultural Sciences & 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, Ecology 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: Life Sciences, 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, Ecology 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, Anatomy & Morphology 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, Other 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: Life Sciences, Biochemistry 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/preprints201808.0082.v1
Subject: Earth Sciences, Environmental Sciences 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: Life Sciences, Other 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/preprints202205.0410.v1
Subject: Social Sciences, Other 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: Life Sciences, Biochemistry 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: Earth Sciences, 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.
ARTICLE | doi:10.20944/preprints202002.0306.v1
Subject: Life Sciences, Microbiology Keywords: Egyptian mongoose; Gut microbiota; Microbial profiling; Bio-ecology; Mediterranean Wild Carnivores
Online: 21 February 2020 (08:02:59 CET)
Egyptian mongoose (Herpestes ichneumon) is a medium-size carnivore that in Europe is restricted to Iberia. The bio-ecology of this species remains to be elucidated in several dimensions, including gut microbiota that is nowadays recognized as a fundamental component of mammals. In this work, we investigated the gut microbiota of this herpestid by single-molecule real-time sequencing of twenty paired male (n=10) and female (n=10) intestinal samples. This culture-independent approach enabled microbial profiling based on 16S rDNA and investigation of taxonomical and functional features. The core gut microbiome of the adult subpopulation was dominated by Firmicutes, Fusobacteria, Actinobacteria, and Proteobacteria. Eight genera were uniquely found in adults and five in non-adults. When comparing gut bacterial communities across sex, four genera were exclusive of females and six uniquely found in males. Despite these compositional distinctions, alpha- and beta-diversity analyses showed no statistically significant differences across sex or between adult and non-adult specimens. However, males presented a significantly higher abundance of amino acid and citrate cycle metabolic pathways, compared to the significant overrepresentation in females of galactose’ metabolic pathways. Adults showed a significantly higher abundance of cationic antimicrobial peptide resistance pathways, while non-adults bared a significant overrepresentation of two-component systems associated with antibiotic synthesis, flagellin production and chemotaxis control. This study adds new insights into mongoose bio-ecology palette, highlighting taxonomical and functional microbiome dissimilarities across sex and age classes, possibly related to primary production resources and life-history traits that impact on behavior, diet and gut ecosystem.
ARTICLE | doi:10.20944/preprints201909.0202.v1
Subject: Engineering, Energy & Fuel Technology Keywords: Plants-Microbial Fuel Cells; clean energy; electric potential; power output; resistivity
Online: 18 September 2019 (08:21:05 CEST)
Plants Microbial Fuel Cells (PMFC) is a new technology that generates electricity in a renewable, clean and sustainable way. In spite of these advantages, it still faces limitations in power generation and current density, reaching lower production values than other renewable technologies. Different studies maintain that the high resistivity of the cathode is the main limitation in the generation of energy; therefore, non-metallic materials to obtain a better performance are replacing the metallic electrodes. The implementation of these materials applied to PMFC requires a complex interdisciplinary work. Through three experimental tests using metallic electrodes for the extraction of electrons, this research study shows that the treatment of the substrate with natural materials, the volume plant roots, and substrate temperature and humidity control have a significant influence in the increase of the electric potential and the generated current.
ARTICLE | doi:10.20944/preprints201903.0167.v1
Subject: Engineering, Energy & Fuel Technology Keywords: Bioelectrochemical system; Cation exchange membranes; Ageing of membranes; Microbial electrolysis cell.
Online: 18 March 2019 (09:07:18 CET)
Bioelectrochemical systems (BES) encompass a group of biobased technologies capable of directly converting organic matter into electricity. In these systems, which are derived from conventional electrochemical systems, the ion exchange membrane represents a key element because of its influence on the economic feasibility and on the performance of BES. This study examines the impact of long-term operation of a BES on the mechanical, chemical and electrochemical properties of five different kind of cation exchange membranes (Nafion-117, CMI-7001, Zirfon UTP 500, FKE and FKB) through several techniques: (i) scanning electron microscopy (SEM) and atomic force microscopy (AFM) to assess the changes on the membranes surface, (ii) thermogravimetric analysis (TGA) to evaluate the structural stability of the membranes, and (iii) ion exchange capacity (IEC) to monitor any change in their electrochemical properties. Results confirmed that there is not an ideal membrane for BES. While Nafion and CMI-7000 exhibited the strongest chemical structure, they also underwent the highest fouling as revealed by a fast increase in surface roughness.
ARTICLE | doi:10.20944/preprints201809.0300.v1
Subject: Earth Sciences, Environmental Sciences Keywords: marginal soil; basalt material; land degradation; native plant species; microbial community
Online: 17 September 2018 (10:54:36 CEST)
The plant-microbe-soil nexus is critical in maintaining biogeochemical balance of the biosphere. However, soil loss and land degradation are occurring at alarmingly high rates, with soil loss exceeding soil formation rates. This necessitates evaluating marginal soils for their capacity to support and sustain plant growth. In a greenhouse study, we evaluated the capacity of marginal incipient basaltic parent material to support native plant growth, and the associated variation in soil microbial community dynamics. Three plant species, native to the Southwestern Arizona-Sonora region were tested with three soil treatments including basaltic parent material, parent material amended with 20% compost, and potting soil. The parent material with and without compost supported germination and growth of all the plant species, though germination was lower than the potting soil. A 16S rRNA amplicon sequencing approach showed Proteobacteria to be the most abundant phyla in both parent material and potting soil, followed by Actinobacteria. Microbial community composition had strong correlations with soil characteristics but not plant attributes within a given soil material. Predictive functional potential capacity of the communities revealed chemoheterotrophy as the most abundant metabolism within the parent material, while photoheterotrophy and anoxygenic photoautotrophy were prevalent in the potting soil. These results show that marginal incipient basaltic soil has the ability to support native plant species growth, and non-linear associations may exist between plant-marginal soil-microbial interactions.
ARTICLE | doi:10.20944/preprints201809.0014.v1
Subject: Engineering, Energy & 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.
REVIEW | doi:10.20944/preprints201808.0488.v1
Subject: Chemistry, Medicinal Chemistry Keywords: Sarcophyton; Sinularia; Lobophytum; new compounds; anti-microbial; anti-inflammatory; anti-tumoral
Online: 29 August 2018 (09:03:48 CEST)
Work reviews the new isolated isolated cembranoid diterpene derivatives from species belonging to the family Alcyoniidae, which comprises the genera Sarcophyton, Sinularia, and Lobophytum as well as their biological properties, during 2016–2017. The compilation permitted to conclude that much more new cembranoid diterpenes were found in the soft corals of the genus Sarcophyton sp. (33 new compounds) than in those belonging to the genera Lobophytum (17) or Sinularia (8). Several methods have been used for identifying these new compounds, after extraction with organic solvents and fractionation. The fractions obtained, in some cases, were followed by TLC, and again subjected to chromatographic procedures, including semi-preparative HPLC. Beyond the chemical composition, the biological properties were also evaluated, namely anti-microbial against several Gram-positive and Gram-negative bacteria and fungi, anti-inflammatory and anti-tumoral against several types of cancer cells. Although the biological activities detected in almost all samples, they were not outstanding ones.
ARTICLE | doi:10.20944/preprints201808.0479.v1
Subject: Biology, Ecology Keywords: COS production; COS uptake; Carbonic anhydrase; nitrate; ammonium; sulfur; microbial community
Online: 29 August 2018 (01:07:13 CEST)
Soils are an important COS sink. However they can also act as sources of COS to the atmosphere. Here we demonstrate that variability in the soil COS sink and source strength is strongly linked to available soil inorganic nitrogen (N) content across a diverse range of biomes in Europe. We revealed in controlled laboratory experiments that N fertilisation simultaneously decreases the COS sink strength of soils while increasing the COS production rate. Furthermore, we found strong links between variations in the two gross COS fluxes, microbial biomass and nitrate and ammonium contents, providing new insights into the mechanisms involved. Our findings provide evidence for how soil-atmosphere exchange of COS is likely to vary spatially and temporally, a necessary step for constraining the role of soils and land use in the COS mass budget.
REVIEW | doi:10.20944/preprints202205.0179.v1
Subject: Biology, Ecology Keywords: predator-prey interactions; evolution; prey defense; microbial communities; food webs; multiple defenses
Online: 13 May 2022 (06:23:39 CEST)
Predation is a driving force of organismal ecology and evolution. Predator-prey interactions, constrained by other environmental factors and historical contingency, shape physical and behavioral phenotypes of organisms on both sides of the interaction arrow. Yet despite the universality of trophic interactions in biology, study of the ecology and evolution of anti-predator defense is challenging because these interactions tend to be brief and unpredictable, and thus gathering direct evidence requires patience and serendipity. The evolution of prey defenses can be studied by DNA sequencing followed by phylogenetic analysis, and the ecology can be studied by field observation and bringing tractable systems into the lab. However, animal models generally do not allow genetic manipulation, strict control of environmental variables, or detailed observation of evolution in real time, all of which are important for demonstrating evolutionary causes and consequences. Developing complementary microbial predator-prey systems can help overcome this hurdle. There is an extensive body of work on microbial experimental evolution, and many microbes come with well-characterized genomes and established methods for genetic manipulation. As understanding of microbial ecology and the mechanisms of their trophic interactions grows apace, these systems are poised to make valuable contributions to our understanding of how predator behaviors evolve, why certain anti-predator defenses evolve and not others, and how multiple defenses function together in a single defense portfolio. These systems will enable us to both test hypotheses formulated from the study of larger organisms and to propose new ones that can be tested in larger organisms with existing methods.
ARTICLE | doi:10.20944/preprints202008.0664.v1
Subject: Engineering, Other Keywords: Microbial electrolysis cells; Linear sweep voltammetry; Counter electrode; Coefficient of variation; Reproducibility
Online: 30 August 2020 (11:45:33 CEST)
Electrode is a key component in a microbial electrolysis cell (MEC) and it needs significant improvement for practical implementation of MEC. For effective development of electrode technology, accurate and reproducible analytical methods are very important. Linear sweep voltammetry (LSV) is an essential analytical method for evaluating electrode performance; however, it has not been firmly established yet in the MEC field. In this study, biological brush (BB), abiotic brush (AB), Pt wire (PtW), stainless steel wire (SSW) and mesh (SSM)) were tested to explore the most suitable counter electrode in different medium conditions. Coefficient of variation (CV) for Imax of LSV were comparatively analyzed. In BB-anode LSV, SSW (0.48%) and SSM (2.17%) showed higher reproducibility as a counter electrode. In SSM-cathode LSV, BB (1.76%) and PtW (2.01%) produced more reproducible results. In the Ni-AC-SSM-cathode LSV, PtW (3.54%) and BB (8.81%) produced more reproducible result. It shows electrode used in the operation is an appropriate counter electrode in the acetate-added condition. However, in the absence of acetate, PtW (1.24%) and BB (1.71%) produced more reproducible results in SSM cathode and PtW (0.61%) and SSW (1.21%) did in the Ni-AC-SSM-cathode, showing PtW is an appropriate counter electrode. These results also shows that PtW is an appropriate counter electrode in cathode LSV.
ARTICLE | doi:10.20944/preprints202007.0539.v1
Subject: Earth Sciences, Environmental Sciences Keywords: Total organic carbon; Total nitrogen; Soil microbial biomass; Vegetation types; Hongqipao reservoir
Online: 23 July 2020 (08:13:39 CEST)
This study investigated the spatial variability of soil organic carbon (SOC), total nitrogen (TN), soil microbial biomass carbon (SMBC) and soil microbial biomass nitrogen (SMBN) in Hongqipao reservoir dominated by different vegetation types and the possible relationships with other soil properties. Top 0–50cm soil samples were collected in sites dominated by different vegetation types within the reservoir littoral zone. There was high spatial variability for SOC, TN, SMBC and SMBN in the Hongqipao reservoir. In addition, the SOC, TN, SMBC and SMBN contents decreased with increasing soil depth. This could be attributed by the fact that when plants detritus decompose, most of their organic matter is mineralized and a new soil layer which contains a greater amount of organic carbon is formed at the top. According to Pearson's correlation values and redundancy analysis (RDA) results, SOC was significantly and positively correlated with TN likely because the vegetation organic matter and liter could be the main nitrogen sources. Similarly, soil moisture content (MC) was significant positive correlated with SOC and TN. Conversely, BD was significant negative correlated with SOC and TN contents in the 0-50 cm soil profiles. However, no significant correlations were observed between SOC, TN, SMBC and SMBN contents and soil pH values. SMBN was significantly and positive correlated with C:N ratio and BD and negative related with MC. Multiple linear regression model revealed that all measures soil properties in this study could explain higher significant variability of the response variables (SOC, TN, SMBC and SMBN contents). This implies that all the measured soil variables within the different vegetation types in the reservoir played a crucial role in determining the contents of SOC, TN, SMBC and SMBN. This study further suggests that vegetation types play a major role in determining the spatial characteristics of SOC and TN. Any changes in the vegetation types in the reservoir may influence the distribution of SOC and TN. This may affect the global carbon budget and the atmospheric greenhouse gas concentration significantly.
Subject: Engineering, Other Keywords: bioelectrochemical systems; in situ treatment; groundwater remediation; bioelectroremediation; denitrification; microbial electrochemical technologies
Online: 17 January 2020 (11:08:18 CET)
Groundwater contamination is an ever-growing environmental issue that has attracted much and undiminished attention for the past half century. Groundwater contamination may originate from both anthropogenic (e.g., hydrocarbons) and natural compounds (e.g., nitrate and arsenic); to tackle the removal of these contaminants, different technologies have been developed and implemented. Recently, bioelectrochemical systems (BES) have emerged as a potential treatment for groundwater contamination, with reported in situ applications that showed promising results. Nitrate and hydrocarbons (toluene, phenanthrene, benzene, BTEX and light PAHs) have been successfully removed, due to the interaction of microbial metabolism with poised electrodes, in addition to physical migration due to the electric field generated in a BES. The selection of proper BESs relies on several factors and problems, such as the complexity of groundwater and subsoil environment, scale-up issues, and energy requirements that need to be accounted for. Modeling efforts could help predict case scenarios and select a proper design and approach, while BES-based biosensing could help monitoring remediation processes. In this review, we critically analyze in situ BES applications for groundwater remediation, focusing in particular on different proposed setups, and we identify and discuss the existing research gaps in the field.
ARTICLE | doi:10.20944/preprints201912.0401.v1
Subject: Life Sciences, Microbiology Keywords: microbial eukaryotes; phylogeography; marine-freshwater transitions; evolutionary radiation; species flocks; Lake Baikal
Online: 31 December 2019 (03:57:14 CET)
Ancient lakes are among the most interesting models for evolution studies, because their biodiversity is the result of a complex combination of migration and speciation. Here, we investigate the origin of single celled planktonic eukaryotes from the oldest lake in the world – Lake Baikal. By using 18S rDNA metabarcoding we recovered 1,427 Operational Taxonomic Units (OTUs) belonging to protists populating surface waters (1-50 meters) and belonging to pico- and nano-plankton size fractions. The recovered communities resembled other lacustrine freshwater assemblages found elsewhere, especially the unclassified protists. However, our results suggest that a fraction of Baikal protists originated evolutionary recently from marine/brackish ancestors. Moreover, our results suggest that rapid radiation may have occurred among some protist taxa, partially mirroring what was already shown for multicellular organisms in Lake Baikal. We found potential species flocks in Stramenopiles, Alveolata, Opisthokonta, Archaeplastida, Rhizaria and Hacrobia. Putative flocks predominated in Chrysophytes, which are highly diverse in Lake Baikal. Some of the species, especially those from these flocks, may be endemic from Lake Baikal, because their 18S rDNA differed > 10% from known DNA. Overall, our study points to novel diversity of planktonic protists in Lake Baikal, some of which may have emerged in situ after evolutionary diversification.
ARTICLE | doi:10.20944/preprints201911.0364.v1
Subject: Chemistry, Organic Chemistry Keywords: mannich reaction; 1,2,4-triazine; pyrimidine; 1,2,4-triazole; n-heterocycles; anti-microbial activity
Online: 29 November 2019 (02:26:36 CET)
In our tactic to construct bio-active molecules, a series of novel pyrimido[2,1-c][1,2,4]triazine-3,4-diones based heterocycles, were synthesized and evaluated for their in vitro antimicrobial impacts. The exploratory bioassay results declared that, the majority of the evaluated compounds exhibited considerable anti-microbial activity comparable to the reference drugs. Conjugates 15j, 15f, 15i, 15h, 15g and 15a were found to be the most potent antibacterial, indicating that conjugates bearing electron-attracting substituents exhibited higher potency than these with electron-releasing substituents.
ARTICLE | doi:10.20944/preprints201710.0122.v1
Subject: Biology, Other Keywords: microbial communities; host-microbe interactions; mathematical modelling; diatoms; synthetic ecology; algal biotechnology
Online: 17 October 2017 (17:37:49 CEST)
The pennate diatom Phaeodactylum tricornutum is a model organism able to synthesize industrially-relevant molecules. Commercial-scale cultivation currently requires large monocultures, prone to bio-contamination. However, little is known about the identity of the invading organisms. To reduce the complexity of natural systems, we systematically investigated the microbiome of non-axenic P. tricornutum cultures from a culture collection in reproducible experiments. The results revealed a dynamic bacterial community that developed differently in “complete” and “minimal” media conditions. In complete media, we observed an accelerated “culture crash”, indicating a more stable culture in minimal media. The identification of only four bacterial families as major players within the microbiome suggests specific roles depending on environmental conditions. From our results we propose a network of putative interactions between P. tricornutum and these main bacterial factions. We demonstrate that, even with rather sparse data, a mathematical model can be reconstructed that qualitatively reproduces the observed population dynamics, thus indicating that our hypotheses regarding the molecular interactions are in agreement with experimental data. Whereas the model in its current state is only qualitative, we argue that it serves as a starting point to develop quantitative and predictive mathematical models, which may guide experimental efforts to synthetically construct and monitor stable communities required for robust upscaling strategies.
ARTICLE | doi:10.20944/preprints201704.0122.v1
Subject: Earth Sciences, Environmental Sciences Keywords: crust type; soil depth; physicochemical properties; enzyme; microbial biomass carbon and nitrogen
Online: 19 April 2017 (11:23:58 CEST)
This study investigated the effects of soil crust development on the underlying soil properties. The field sampling work was conducted in June 2016 in the Hobq Desert in Inner Mongolia, North China. Soil crust samples and 0–6, 6–12, 12–18, 18–24, 24–30 cm deep underlying soil samples were taken from five representative areas of different soil crust development stages. All samples were analyzed for physicochemical properties including water content, bulk density, aggregate content, organic matter content, enzyme activities, and microbial biomass carbon and nitrogen. The results showed that the thickness, water content, macroaggregate (>250 μm) content, organic matter content, microbial biomass and enzyme activities of the soil crusts gradually increased along the soil crust development gradient, while the bulk density of the soil crusts decreased. Meanwhile, the physicochemical and biological properties of the soils below the algal and moss crusts were significantly ameliorated when compared with the physical crust. Moreover, the amelioration effects were significant in the upper horizons (approx. 0–12 cm deep) and diminished quickly in the deeper soil layers.
ARTICLE | doi:10.20944/preprints202012.0391.v1
Subject: Life Sciences, Biochemistry Keywords: Host-microbe; Zebrafish; Shewanella; Symbiosis; Microbial evolution; Msh pilus; Adaptation; Biofilms; Fitness; Colonization
Online: 15 December 2020 (16:34:25 CET)
Symbioses between animals and bacteria are ubiquitous. To better understand these relationships, it is essential to unravel how bacteria evolve to colonize hosts. Previously, we serially passaged the free-living bacterium, Shewanella oneidensis, through the digestive tracts of germ-free larval zebrafish (Danio rerio) to uncover the evolutionary changes involved in the initiation of a novel symbiosis with a vertebrate host. After 20 passages, we discovered an adaptive missense mutation in the mshL gene of the msh pilus operon, which improved host colonization, increased swimming motility, and reduced surface adhesion. In the present study, we have determined that this mutation was a loss-of-function mutation and found that it improved zebrafish colonization by augmenting S. oneidensis representation in the water column outside larvae through a reduced association with environmental surfaces. Additionally, we found that strains containing the mshL mutation were able to immigrate into host digestive tracts at higher rates per capita. However, mutant and evolved strains exhibited no evidence of a competitive advantage after colonizing hosts. Our results demonstrate that bacterial behaviors outside the host can play a dominant role in facilitating the onset of novel host associations.
REVIEW | doi:10.20944/preprints201810.0763.v1
Subject: Engineering, Energy & Fuel Technology Keywords: Microbial fuel cell (MFC); fuel cell elements; design; energy generation; Scaling up; configuration
Online: 2 November 2018 (10:04:38 CET)
Fossil fuels and carbon origin resources are affecting our environment. Therefore, alternative energy sources have to be established to co-produce energy along with fossil fuels and carbon origin resources until it is the right time to replace them. Microbial Fuel Cell (MFC) is a promising technology in the field of energy production. Compared to the conventional power sources it is more efficient and not controlled by the Carnot cycle. Its high efficiencies, low noise, and less pollutant output could make it revolutionize in the power generation industry with a shift from centrally located generating stations and long-distance transmission lines to dispersed power generation at load sites. In this review, several characteristics of the MFC technology will be highlighted. First, a brief history of abiotic to biological fuel cells and subsequently, microbial fuel cells is presented. Second, the focus is then shifted to elements responsible for the making MFC working with efficiency. Setup of the MFC system for every element and their assembly is then introduced, followed by an explanation of the working machinery principle. Finally, microbial fuel cell designs and types of main configurations used are presented along with scalability of the technology for the proper application.
ARTICLE | doi:10.20944/preprints201809.0593.v1
Subject: Earth Sciences, Environmental Sciences Keywords: mariculture; aquaculture; community restoration; conservation ecology; Native Hawaiian fishpond; microbes; microbial source tracking
Online: 30 September 2018 (04:49:28 CEST)
In Hawaiʻi, the transition from customary subsistence flooded taro agroecosystems, which regulate stream discharge rate trapping sediment and nutrients, to a plantation-style economy (c. the 1840s) led to nearshore sediment deposition - smothering coral reefs and destroying adjacent coastal fisheries and customary fishpond mariculture. To mitigate sediment transport, Rhizophora mangle was introduced in estuaries across Hawai’i (c. 1902) further altering fishpond ecosystems. Here, we examine the impact of cultural restoration between 2012-2018 at Heʻeia Fishpond, a 600-800-year-old walled fishpond. Fishpond water quality was assessed by calculating water exchange rates, residence times, salinity distribution, and abundance of microbial indicators prior to and after restoration. We hypothesized that R. mangle removal and concomitant reconstruction of sluice gates would increase mixing and decrease bacterial indicator abundance in the fishpond. We find that Heʻeia Fishpond’s physical environment is primarily tidally driven; wind forcing and river flux are secondary drivers. Post-restoration, two gates in the northeastern region account for >80% of relative flux in the fishpond. Increase in exchange rates during spring and neap tide and shorter minimum water residence time corresponded with the reconstruction of a partially obstructed 56 m gap together with the installation of an additional sluice gate in the fishpond wall. Lower mean salinities post-restoration suggests increased freshwater influx due to R. mangle removal. Spatial distribution of microbial bio-indicator species inversely correlated with salinity. Average abundance of Enterococcus and Bacteroidales did not significantly change after restoration efforts, however, average abundance of a biomarker specific to birds nesting in the mangroves decreased significantly after restoration. This study demonstrates the positive impact of biocultural restoration regimes on water flushing and water quality parameters, encouraging the prospect of revitalizing this and other culturally and economically significant sites for sustainable aquaculture in the future.
ARTICLE | doi:10.20944/preprints201802.0067.v1
Subject: Life Sciences, Microbiology Keywords: external resistances; soil microbial fuel cells; paddy soil; Geobacter; arsenic; iron; organic matter
Online: 8 February 2018 (03:29:46 CET)
Soil microbial fuel cells (sMFC) are a novel technique that use organic matters in soils as an alternative energy source. External resistance (ER) is a key factor influencing sMFC performance and, furthermore, alters the soil’s biological and chemical reactions. However, little information is available on how the microbial community and soil component changes in sMFC with different ER. Therefore, the effects of anodes of sMFC at different ER (2000 Ω, 1000 Ω, 200 Ω, 80 Ω and 50 Ω) were examined by measuring organic matter (OM) removal efficiency, trace elements in porewater and bacterial community structure in contaminated paddy soil. The results indicated that ER has significant effects on sMFC power production, OM removal efficiency and bacterial beta diversity. Moreover ER influences iron, arsenic and nickel concentration as well in soil porewater. In particular, greater current densities were observed at lower ER (2.4mA, 50Ω) compared to a higher ER (0.3mA, 2000Ω). The removal efficiency of OM increased with decreasing ER whereas it decreased with soil distance away from the anode. Furthermore, principal coordinate analysis (PCoA) revealed that ER may shape the bacterial communities that develop in the anode vicinity but have minimal effect on that of the bulk soil. The current study illustrates that lower ER can be used to selectively enhance the relative abundance of electrogenic bacteria and lead to high OM removal.
REVIEW | doi:10.20944/preprints202111.0482.v1
Subject: Earth Sciences, Environmental Sciences Keywords: Solute Transport; Bio-geo-chemical reactions; Dispersion; Mixing; Heterogeneity; Effective transport; Microbial communities, Biofilms
Online: 25 November 2021 (15:53:41 CET)
Reactive transport (RT) couples bio-geo-chemical reactions and transport. RT is important to understand numerous scientific questions and solve some engineering problems. RT is highly multidisciplinary, which hinders the development of a body of knowledge shared by RT modelers and developers. The goal of this paper is to review the basic conceptual issues shared by all RT problems, so as to facilitate advance along the current frontier: biochemical reactions. To this end, we review the basic equations to point that chemical systems are controlled by the set of equilibrium reactions, which are easy to model, but whose rate is controlled by mixing. Since mixing is not properly represented by the standard advection-dispersion equation (ADE), we conclude that this equation is poor for RT. This leads us to review alternative transport formulations, and the methods to solve RT problems using both the ADE and alternative equations. Since equilibrium is easy, difficulties arise for kinetic reactions, which is especially true for biochemistry, where numerous frontiers are open (how to represent microbial communities, impact of genomics, effect of biofilms on flow and transport, etc.). We conclude with the basic 10 issues that we consider fundamental for any conceptually sound RT effort.
REVIEW | doi:10.20944/preprints202111.0175.v1
Subject: Biology, Other Keywords: atherosclerotic cardiovascular disease (ACVD); atherosclerosis; gut dysbiosis; immune system; gut microbial metabolites; SCFAs; TMAO
Online: 9 November 2021 (13:45:20 CET)
Atherosclerosis is a leading cause of cardiovascular disease and mortality worldwide. Alterations in the gut microbiota composition, known as gut dysbiosis, have been shown to contribute to atherosclerotic cardiovascular disease (ACVD) development through several pathways. Disruptions in gut homeostasis are associated with activation of immune processes and systemic inflammation. The gut microbiota produces several metabolic products, namely trimethylamine (TMA), which is used to produce the proatherogenic metabolite trimethylamine-N-oxide (TMAO). Short chain fatty acids (SCFAs), including acetate, butyrate, and propionate, and certain bile acids (BAs) produced by the gut microbiota lead to inflammation resolution and decrease atherogenesis. Chronic low-grade inflammation is associated to common risk factors for atherosclerosis, including metabolic syndrome, type 2 diabetes mellitus (T2DM), and obesity. Novel strategies for reducing ACVD include the use of nutraceuticals such as resveratrol, modification of glucagon-like peptide 1 (GLP-1) levels, supplementation with probiotics, and administration of prebiotic SCFAs and BAs. Investigation into the relationship between the gut microbiota and its metabolites, and the host immune system could reveal promising insight into ACVD development, prognostic factors, and treatments.
REVIEW | doi:10.20944/preprints202105.0451.v1
Subject: Life Sciences, Biochemistry Keywords: eco-evo-devo; evolution of multicellularity; fruiting body; life-history evolution; microbial evo-devo
Online: 19 May 2021 (14:37:11 CEST)
Microbes have evolved many fascinating and complex ways of interacting with conspecifics. Perhaps one of the most interesting is aggregative multicellularity, wherein independent cells come together and adhere to one another in order to form a larger entity. The fundamental benefits of active aggregation into multicellular groups generally remain unclear, and there are many open questions about what selective pressures led to the evolution of this behavior in various eukaryotic and prokaryotic taxa, most notably the dictyostelids and the myxobacteria. Aggregative multicellularity can be partitioned into three main phases: coming together, staying together as a group, and disaggregation. Different selective pressures may have led to adaptations unique to each phase. While aggregative microbial systems generally form elevated multicellular structures such as fruiting bodies, these can vary in complexity and morphology even among closely related species. What evolutionary forces shaped such morphological diversification remains unknown. Strains that are not genetically identical can coaggregate, which can impact group-level function either positively through functional synergy or negatively through harmful exploitation. Such chimerism within aggregates is likely to have played important roles in shaping the evolution of microbial multicellularity. Much further research is needed into the evolutionary forces and processes leading to and shaping the many forms of microbial aggregation.
ARTICLE | doi:10.20944/preprints202008.0361.v1
Subject: Engineering, Other Keywords: Biodegradation of Ciprofloxacin; 3D-BER System; Denitrification; Microbial communities; Low C/N Wastewater treatment.
Online: 17 August 2020 (10:26:08 CEST)
Emerging pollutants as pharmaceuticals have been focusing international attention for few decades. Ciprofloxacin (CIP) is a common drug widely found in effluents from hospitals, industrial and different wastewater treatment plants, as well as rivers. In this work, the lab-scale 3D-BER system was established, and more than 90% of the antibiotic CIP removal from the Low C/N wastewater. Best results were obtained with current intensity, and different C/N ratio significantly improve the removal of CIP and nitrates, when the ideal conditions were; C/N = 1.5-3.5, pH =7.0-7.5, and I = 60 mA. The highest removal efficiency of CIP = 94.20 %, NO3--N= 95.53 % and total nitrogen (TN) = 84.27 %, respectively. In this novel system, the autotrophic-heterotrophic denitrifying bacteria played vital role for the removal of CIP and enhanced denitrification process. Thus, autotrophic denitrifying bacteria uses CO2 and H2 as carbon sources to reduce nitrates to N2. This system has the assortment and prosperous community revealed at the current intensity of 60 mA, and the analysis of bacterial community structure in effluent samples fluctuates under different condition of C/N ratios. According to the results of LC-MS/MS analysis, the intermediate products were proposed after efficient biodegradation of CIP. Microbial community on biodegrading was mostly found at phylum, and class level was dominantly responsible for the NO3--N and biodegradation of CIP. This work can provide some new insights towards the biodegradation of CIP and the efficient removal of nitrates from low C/N wastewater treatment by the novel 3D-BER system.
ARTICLE | doi:10.20944/preprints202108.0104.v1
Subject: Biology, Anatomy & Morphology Keywords: quantitative metagenomics; microbiome; obesity; gut microbiota; microbial DNA extraction; sequencing; Simulation; Oxford Nanopore Technologies; MinION
Online: 4 August 2021 (09:44:24 CEST)
Background: The gut microbiome plays a major role in chronic diseases, of which several are characterized by an altered composition and diversity of bacterial communities. Large-scale sequencing projects allowed characterizing the perturbations of these communities. However, translating these discoveries into clinical applications remains a challenges. To facilitate routine implementation of microbiome profiling in clinical settings, portable, real-time, and low-cost sequencing technologies are needed. Results: Here, we propose a computational and experimental protocol for whole genome quantitative metagenomics studies of human gut microbiome with Oxford Nanopore sequencing technology (ONT) that could be applied to other microbial ecosystems. We developed a bioinformatic protocol to analyse ONT sequences taxonomically and functionally and optimized pre-analytic protocols including stool collection and DNA extraction methods to maximize read length. This is a critical parameter for the sequence alignment and classification. Our protocol was evaluated using simulations of metagenomic communities which reflect naturally occuring compositional variations. Next, we validated both protocols using stool samples from a bariatric surgery cohort, sequenced with ONT, Illumina and SOLiD technologies. Results revealed similar diversity and microbial composition profiles. Conclusion: This protocol can be implemented in the clinical or research setting, bringing rapid personalized whole genome profiling of target microbiome species.
ARTICLE | doi:10.20944/preprints202101.0045.v1
Subject: Life Sciences, Biochemistry Keywords: Kombucha tea; microbial diversity; bacterial cellulose; Komagataeibacter xylinus; repetitive elements sequence-based rep-PCR; typing
Online: 4 January 2021 (13:24:41 CET)
Bacterial cellulose (BC) is receiving great attention due to its unique properties such as high purity, water retention capacity, high mechanical strength, and biocompatibility. However, the production of BC has been limited because of high cost and low productivity. In this light, the isolation of new BC producing bacteria and selection of high productive strains became a promising issue. Kombucha tea is a fermented beverage in which the bacteria fraction of the microbial community is composed mostly by strains belonging to the genus Komagataeibacter. In this study Kombucha tea production trials were performed starting from a previous batch, and bacterial isolation was conducted along cultivation time. From the whole microbial pool, 46 isolates were tested for their ability in producing BC. The obtained BC yield ranged from 0.59 g/L, for the isolate K2G36, to 23 g/L for K2G30 used as the reference strain. The genetic intraspecific diversity of the 46 isolates was investigated using two repetitive-sequence-based PCR typing methods, which are the enterobacterial repetitive intergenic consensus (ERIC) elements and the (GTG)5 sequences, respectively. The results obtained using two different approaches revealed the suitability of the fingerprints techniques, showing a discrimination power, calculated as D index, of 0.94 for (GTG)5 rep-PCR and 0.95 for ERIC rep-PCR. In order to improve the sensitivity of the applied method, a combined model from the two genotyping experiments was performed, allowing to discriminate among strains.
CONCEPT PAPER | doi:10.20944/preprints202005.0211.v2
Subject: Keywords: Thermoregulation; microbial metabolism; overflow metabolism; biofilms; public goods; social evolution; ecological competition; fever; bacteriophage defense
Online: 17 July 2020 (09:35:22 CEST)
Many microbes live in habitats below their optimum temperature. Retention of metabolic heat by aggregation or insulation would boost growth. Generation of excess metabolic heat may also provide benefit. A cell that makes excess metabolic heat pays the cost of production, whereas the benefit may be shared by neighbors within a zone of local heat capture. Metabolic heat as a shareable public good raises interesting questions about conflict and cooperation of heat production and capture. Metabolic heat may also be deployed as a weapon. Species with greater thermotolerance gain by raising local temperature to outcompete less thermotolerant taxa. Metabolic heat may provide defense against bacteriophage attack, by analogy with fever in vertebrates. This article outlines the theory of metabolic heat in microbial conflict and cooperation, presenting several predictions for future study.
ARTICLE | doi:10.20944/preprints202006.0209.v1
Subject: Engineering, Energy & Fuel Technology Keywords: anode maturation time; microbial fuel cell (MFC); linear sweep voltammetry (LSV) polarization; cyclic voltammetry (CV)
Online: 17 June 2020 (08:10:59 CEST)
To obtain an accurate and reproducible experimental results in microbial fuel cell (MFC), it is important to know ‘anode maturation biofilm’ to produce a stable and maximum performance. For this purpose, four single chamber MFCs were tested in this study. The linear sweep voltammetry (LSV) polarization tests illustrated that maximum power densities of three MFCs became stable after 9 weeks. Although there were variations afterwards, such variations were negligible. Average maximum power densities from the 9th to the 17th week were 2,990 mW/m2 (MFC-4), 2,983 mW/m2 (MFC-2), 2,368 mW/m2 (MFC-3) and 837 mW/m2 (MFC-1). Polarization resistance shows that MFC-1 had much larger anode resistance (36.6-85.4 Ω) than the other MFCs (1.7-11.6 Ω). Anodic cyclic voltammetry (CV) shows that current production increased over time and MFC-1 had much smaller current production (24.4 mA) than the other MFCs (31.0-34.9 mA) at 17th week. The increased current production indicates anode biofilm became more mature over time, but overall cell performance did not increased accordingly. Possibly due to the bad inoculation, MFC-1 showed the lowest performance. However, its performance was restored to the initial performance and anode resistance was reduced by 47% at 17th week. This study shows that the optimum anode maturation time is 9 weeks and that bioanode performance is a key factor for MFC performance. This study also shows than LSV polarization and CV tests are accurate and non-destructive measurement methods for diagnosing anode performance.
REVIEW | doi:10.20944/preprints202005.0329.v1
Subject: Life Sciences, Other Keywords: sustainable agriculture; carbon sequestration; crop productivity; soil acidification; soil organic matter; pyrolysis; microbial activity, biochar
Online: 20 May 2020 (11:04:28 CEST)
The sustainable production of food faces formidable challenges. Foremost is the availability of arable soils, which have been ravaged by the overuse of fertilizers and detrimental soil management techniques. As such, maintenance of soil quality, and reclamation of marginal soils, has become an increasingly important endeavor. Recently, there has been emerging interest in the use of biochar, a carbon rich, porous material thought to improve various aspects of soil performance. Biochar (BC) is produced through the thermochemical decomposition of organic matter at high temperature in an oxygen limited environment, in a process known as pyrolysis. Importantly, the source of organic material, or ‘feedstock,’ used in this process and different parameters of pyrolysis, especially temperature, determine the chemical and physical properties of biochar. Incorporation of BC impacts soil-water relations, tilth and nutrient status, pH, soil organic matter (SOM), and microbial activity. Soil amendment with BC has been shown to have an overall positive impact on soil health and crop productivity; however, initial soil properties need to be considered prior to the application of BC. There is an urgent need to understand the effects of long-term field application of BC and how it influences the soil microcosm. This knowledge will facilitate predictable enhancement of crop productivity and meaningful carbon sequestration.
COMMUNICATION | doi:10.20944/preprints202004.0253.v1
Subject: Life Sciences, Other Keywords: Genomic Epidemiology; GenomeTrakr; microbial pathogen surveillance, NCBI submission; whole genome sequencing; QA/QC; One Health
Online: 16 April 2020 (05:26:42 CEST)
The holistic approach of One Health, which sees human, animal, plant, and environmental health as a unit, rather than discrete parts, requires not only interdisciplinary cooperation, but standardized methods for communicating and archiving data, enabling participants to easily share what they have learned and allow others to build upon their findings.Ongoing work by NCBI and the GenomeTrakr project illustrates how open data platforms can help meet the needs of federal and state regulators, public health laboratories, departments of agriculture, and universities. Here we describe how microbial pathogen surveillance can be transformed by having an open access database along with Best Practices for contributors to follow. First, we describe the open pathogen surveillance framework, hosted on the NCBI platform. We cover the current community standards for WGS quality, provide an SOP for assessing your own sequence quality and recommend QC thresholds for all submitters to follow. We then provide an overview of NCBI data submission along with step by step details. And finally, we provide curation guidance and an SOP for keeping your public data current within the database. These Best Practices can be models for other open data projects, thereby advancing the One Health goals of Findable, Accessible, Interoperable and Re-usable (FAIR) data.
ARTICLE | doi:10.20944/preprints202111.0395.v1
Subject: Chemistry, Physical Chemistry Keywords: Tamarind Gum; Hydrogels; Semi-IPNs; Green synthesis; Silver Nanoparticles; Drug Delivery; Chemotherapeutics; HCT116 Cell; Anti-microbial
Online: 22 November 2021 (13:46:47 CET)
Novel pH responsive semi-interpenetrating polymer hydrogels based on tamarind gum-co-poly(acrylamidoglycolic acid) (TMGA) polymers have been synthesized using simple free radical polymerization in the presence of bis[2-(methacryloyloxy)ethyl] phosphate as a crosslinker and potassium persulfate as a initiator. In addition, these hydrogels have been used as templates for green synthesis of silver nanoparticles (13.4±3.6 nm in diameter, TMGA-Ag) by using leaf extract of Teminalia bellirica as reducing agent. Swelling kinetics and equilibrium swelling behavior of the TMGA hydrogels have been investigated in various pH environment the maxium % equilibrium swelling behavior observed i.e., 2882±1.2. The synthesized hydrogels and silver nanocomposites have been characterized by the UV, FTIR, XRD, SEM and TEM. TMGA and TMGA-Ag hydrogels have been investigated to study the characteristics of drug delivery and antimicrobial study. Doxorubicin hydrochloride, a chemotherapeutic agent successfully encapsulated with maximum encapulstaion efficiency i.e., 69.20±1.2 and performed in vitro release studies in pH physiological and gastric environment at 37 ℃. The drug release behavior is examined with kinetic models such as zero order, first order, Higuchi, Hixson Crowell, Korsmeyer-Peppas. These release data was the best fitted with the Korsemeyer-Peppas transport mechanism with n=0.91. Treatment effect on HCT116 Cell, human colon cancer cells were assessed with cell viability and cell cycle analysis. Antimicrobial activity of TMGA-Ag hydrogels is studied against to Staphylococcus aureus and Klebsiella pneumonia. Finally, the results demonstrate that TMGA and TMGA-Ag are promising candidates for anti-cancer drug delivery and inactivation of pathogenic bacteria, respectively.
ARTICLE | doi:10.20944/preprints202001.0043.v1
Subject: Chemistry, Analytical Chemistry Keywords: biosensors; cyclic voltammetry; electrochemical sensors; extracellular electron transfer; extracellular polymeric substances; growth curve; microbial growth phases
Online: 5 January 2020 (16:23:51 CET)
Microbial growth has been of prime importance to the researchers in health and biotechnology industries. It has been known to be closely associated to the secretion of extracellular polymeric substances that help in the formation of colonies. Inter-microbial communication happens within such colonies by means of extracellular electron transfer mediated by the aforementioned polymeric substances. Conventionally, different phases of microbial growth are monitored with the aid of a traditional UV-Visible spectrophotometer by measuring the optical density of the liquid medium at 280 nm. In this paper, we have developed an alternative novel way to sense different growth phases employing electrochemical means i.e. two-terminal cyclic voltammetry. This cyclic voltammetry relies on the extracellular electron transfer mechanism taking place via the polymeric substances secreted by the microorganisms, measured by the temporal area changes in the current-voltage hysteresis curves in the inoculated nutrient broth. This work paves a new way to detect the biological activity in the medium, which can be directly correlated to the population of microorganisms. It would be of immense interest to scientists and researchers working in the field of microbiology as well as in development of biosensors, electrochemical sensors etc. which would be helpful in absence of traditional spectrophotometers.
ARTICLE | doi:10.20944/preprints201912.0239.v1
Subject: Keywords: OptiCell; microbial diversity; gut microbiota; gut health; free-range chickens; caged chickens; SCFA; mucus layer; welfare
Online: 18 December 2019 (05:25:45 CET)
It is of merit to study the appropriate amount of fiber to add to free-range chickens feed to improve the microbial diversity and gut health in times of plant fiber deprivation. OptiCell is a useful source of fiber as a type of eubiotic lignocellulose, and its positive effects on the growth performance and laying performance of chickens has already been proven. However, few researchers have researched the effects of adding OptiCell on the gut microbiota of chickens. In this research we added three different levels of OptiCell (0%, 2% and 4%) to the feed of caged and free-range Bian chickens from September to November, aiming to observe the effects of adding OptiCell and different feeding modes on the gut microbial diversity and gut health of chickens, and aiming to determine an appropriate amount of OptiCell. The results showed that adding OptiCell could increase the thickness of the cecum mucus layer and the abundance of Akkermansia and Faecalibacterium in caged chickens, and 4% OptiCell was optimum. In addition, adding OptiCell increased the microbial diversity and the abundance of the butyrate-producing bacteria Faecalibacterium and Roseburia of fee-range chickens. The α-diversity and the length of the small intestine with 2% OptiCell in free-range chickens were better than with 2% OptiCell in caged chickens. In addition, compared with caged chickens, the free-range chickens had longer small intestine and lower GLP-1. Taken together, an appropriate amount of OptiCell benefitted the microbial diversity and health of chickens; it was necessary to add dietary fiber to the feed of free-range chickens when plant fibers was lacking, and 2% OptiCell was found to be optimum.
ARTICLE | doi:10.20944/preprints201909.0290.v1
Subject: Life Sciences, Microbiology Keywords: microbial antioxidants; bioactive compounds; microwave extract; aspergillus flavus; rice, antioxidant compounds; free radical; phenolic compounds; temperatures
Online: 26 September 2019 (03:39:00 CEST)
The current study aims to study the optimal fermentation conditions for producing microbial bioactive compounds. The microwave parameters consist on 2450 MHz, and 500-watt for 20, 30, and 40 seconds. The solubility of solvents was tested for the extraction of antioxidant compounds from fermented rice (Koji) by A. flavus, Ethyl acetate was the best solvent used for extraction purposes. Antioxidant properties were differentiated by blocking the oxidation of the linoleic acid with an inhibition rate of 73.13% at a concentration of 200 mg/mL, in addition to increasing its effectiveness for free radical extraction and reduction strength by increasing concentrations gradually. The bond ability to irons was lower compared to the EDTA-2Na, in addition to the obtained total content corresponding to phenolic compounds in the ethyl acetate extract of fermented rice (Koji) by A. flavus was 232.11 mg, on the basis of galic acid/mg. The stability of the antioxidant compounds of the ethyl acetate extract of fermented rice (Koji) by A. flavus was also studied; showing stability under neutral conditions, as well as at high temperatures (185 °C during two hours). However, no stability was obtained under acidic and alkaline conditions.
REVIEW | doi:10.20944/preprints201807.0369.v1
Subject: Biology, Plant Sciences Keywords: bioelectrochemical systems (BES); electroactive bacteria (EAB); extracelullar electron transfer (EET); microbial fuel cells (MFC); treatment wetlands
Online: 20 July 2018 (04:03:11 CEST)
Microbial electrochemical technologies (MET) rely on the presence of the metabolic activity of electroactive bacteria for the use of solid-state electrodes for oxidizing different kind of compound, that could lead to the synthesis of chemicals, bioremediation of polluted matrices, the treatment of contaminants of interest, as well as the recovery of energy. Keeping in mind those possibilities, since the beginning of the present century, there has been a growing interest in the use of electrochemical technologies for wastewater treatment, and if possible with simultaneous power generation. In the last years, there has been a growing interest to explore the possibility of merging MET with constructed wetlands, to offer a new option of intensified wetland system that could keep a high performance with a lower footprint. Based on that interest, this paper explains the general principles of MET, and the different known extracellular electron transfer mechanisms ruling the interaction between electroactive bacteria and potential solid-state electron acceptors. Also, the adoption of those principles for the development of MET set-ups for simultaneous wastewater treatment and power generation, and the challenges that the technology face. Ultimately, the most recent developments in set-ups that merges MET with constructed wetlands are presented and discussed.
ARTICLE | doi:10.20944/preprints202208.0026.v1
Subject: Biology, Plant Sciences Keywords: rhizosphere; phyllosphere; endophyte; plant microbiome; plant mycobiome; rare microbiome; fungi; bacteria; microbes; soil microbiology; inoculum; microbial ecology
Online: 1 August 2022 (15:22:30 CEST)
A plant’s health and productivity is influenced by its associated microbes. Although the common microbiome is often thought to be the most influential, significant numbers of rare or uncommon microbes (eg. specialized endosymbionts) may also play an important role in the health and productivity of certain plants in certain environments. To help identify rare/specialized bacteria and fungi in the most important angiosperm plants, we contrasted microbiomes of the shoots, roots and rhizospheres of Arabidopsis, Brachypodium, maize, wheat, sugarcane, rice, tomato, coffee, common bean, cassava, soybean, switchgrass, sunflower, Brachiaria, barley, sorghum, and pea. Plants were grown inside sealed jars on sterile sand or field soil. About 95% and 86% of fungal and bacterial diversity inside plants was uncommon, however judging by read abundance, up to half of the mycobiome consists of uncommon fungal cells, while less than 11% of bacterial endophytes are rare. Uncommon seed transmitted microbiomes consisted mostly of Proteobacteria, Firmicutes, Bacteriodetes, Ascomycetes and Basidiomycetes that most heavily colonized shoots, to a lesser extent roots and least of all rhizospheres. Soil served as a more diverse source of rare microbes than seeds, replacing or excluding the majority of the uncommon seed transmitted microbiome. With the rarest microbes, their colonization pattern could either be the result of stringent biotic filtering by most plants, or uneven/stochastic inoculum distribution in seeds or soil. Several strong plant-microbe associations were observed such as seed transmission to shoots, roots and/or rhizospheres of Sarocladium zeae (maize), Penicillium (pea and Phaseolus), and Curvularia (sugarcane), while robust bacterial colonization from cassava field soil occurred with the cyanobacteria Leptolyngbya into Arabidopsis and Panicum roots, and Streptomyces into cassava roots. Some abundant microbes such as Sakaguchia in rice shoots or Vermispora in Arabidopsis roots appeared in no other samples, suggesting they were infrequent, stochastically deposited propagules from either soil or seed (impossible to know based on the available data). Future experiments with culturing and cross inoculation of these microbes between plants may help us better understand host preferences and their role in plant productivity, perhaps leading to their use in crop microbiome engineering and enhancement of agricultural production.
ARTICLE | doi:10.20944/preprints202106.0404.v1
Subject: Earth Sciences, Atmospheric Science Keywords: Shoreline holy places, unregulated ritual impact, Wastewater and Open-defecation, Physiochemical and Microbial pollution, Gulf of Mannar
Online: 15 June 2021 (12:06:16 CEST)
The present investigation is focused on the forecasting visual observation of the impact of anthropogenic activity on the pilgrimage places located along the coastal environments in Tamil Nadu, India. Devotees performing the unregulated ritual ceremonies, open defecation, waste materials dumping and local municipality discharging wastewater contamination levels were assessed from direct visual surveillance, and by taking photographs and baseline information collected from five different pilgrimage sites. Results showed that ritual ceremonies, wastewater discharges and debris highly contaminated site-III, and found open defecation at site-I. The lack of coastal regulation, pollution awareness, insufficient sanitation facilities and failure to control the commercial and recreational activities have major deleterious effects on the present and future environments of the coastal areas. This is the first attempt conducted by visual assessment of the coastal pollution in pilgrimage places. The results immensely support the recommendation for proper regulation of ritual activities, arrangement of basic sanitation facilities and prohibition of wastewater discharges to prevent waterborne diseases as well as to strictly follow the regional and national level of coastal regulation policy to protect the biological resources of the Gulf of Mannar marine ecosystems.
REVIEW | doi:10.20944/preprints202102.0529.v1
Subject: Chemistry, Analytical Chemistry Keywords: Caver Web; databases; libraries; microbial products; PredictSNPonco; molecular docking; molecular targets; mutations; treatment; virtual screening; web tools
Online: 23 February 2021 (15:59:19 CET)
The development of microbial products for cancer treatment has been in the spotlight in recent years. In order to accelerate the lengthy and expensive drug development process, in silico screening tools are systematically employed, especially during the initial discovery phase. Moreover, considering the steadily increasing number of molecules approved by authorities for commercial use, there is a demand for faster methods to repurpose such drugs. Here we present a review on virtual screening web tools, publicly available databases of molecular targets and libraries of ligands, with the aim to facilitate the discovery of potential anticancer drugs based on microbial products. We provide an entry-level step-by-step description of the workflow for virtual screening of microbial metabolites with known protein targets, as well as two practical examples using freely available web tools. The first case presents a virtual screening study of drugs developed from microbial products using Caver Web, a web tool that performs docking along a tunnel. The second case comprises a comparative analysis between a healthy isocitrate dehydrogenase 1, a mutant that results in cancer, using the recently developed web tool PredictSNPOnco. In summary, this review provides the basic and essential background information necessary for virtual screening experiments, which may accelerate the discovery of novel anticancer drugs.
REVIEW | doi:10.20944/preprints202010.0592.v1
Subject: Life Sciences, Biochemistry Keywords: Microbial consortia; Arbuscular mycorrhizas; Plant growth-promoting rhizobacteria; actinobacteria; Ecosystem functions; Agriculture; Sustainability; Resilience; Multifunctionality; Soil microorganism
Online: 28 October 2020 (14:06:00 CET)
Knowledge of the agricultural soil microbiota, of the microbial consortia that comprise it, and the promotion of agricultural practices that maintain and encourage them, is a promising way to improve soil quality for sustainable agriculture and to provide food security. Although numerous studies have demonstrated the positive effects of beneficial soil microorganisms on crop yields and quality, the use of microbial consortia in agriculture remains low. Microbial consortia have more properties than an individual microbial inoculum, due to the synergy of the microorganisms that make them up. This review describes the main characteristics, ecosystem functions, crop benefits and biotechnological applications of microbial consortia composed of arbuscular mycorrhizal fungi, plant growth promoting bacteria and actinobacteria, to promote the restoration of agricultural soils and, consequently, the quality and health of agricultural crops. The aim is to provide knowledge that will contribute to the development of sustainable and sufficiently productive agriculture, which will adapt in a good way to the pace of the growing human population and to climate change.
REVIEW | doi:10.20944/preprints201804.0060.v1
Subject: Materials Science, Surfaces, Coatings & Films Keywords: volatile renewable resources; microbial infection; secondary plant metabolites; antimicrobial essential oils; biologically-active polymers; plasma-assisted technique
Online: 5 April 2018 (03:32:08 CEST)
The persistent issue of bacterial and fungal colonization of artificial implantable materials and decreasing efficacy of conventional systemic antibiotics used to treat implant-associated infections has led to the development of a wide range of antifouling and antibacterial strategies. This article reviews one such strategy where inherently biologically active renewable resources, i.e. secondary plant metabolites (SPMs) and their naturally occurring combinations (i.e. essential oils) are used for surface functionalization and synthesis of polymer thin films. With a distinct mode of antibacterial activity, broad spectrum of action and diversity of available chemistries, secondary plant metabolites present an attractive alternative to conventional antibiotics. However, their conversion from liquid to solid phase without significant loss of activity is not trivial. Using select examples, this article shows how plasma techniques provide a sufficiently flexible and chemically reactive environment to enable the synthesis of biologically-active polymer-coatings from volatile renewable resources.
ARTICLE | doi:10.20944/preprints201809.0452.v1
Subject: Life Sciences, Biotechnology Keywords: Microbial fuel cell; polymer matrix; immobilization of bacterial cells; interaction of cell membranes with carbon nanotubes, boostconverter accumulation
Online: 24 September 2018 (11:06:23 CEST)
The anode of a microbial fuel cell (MFC) was formed on a graphite electrode and immobilized Gluconobacter oxydans VKM-1280 bacterial cells. Immobilization was performed in chitosan, poly(vinyl alcohol) or N-vinylpyrrolidone-modified poly(vinyl alcohol). Ethanol was used as substrate. The anode was modified using multiwalled carbon nanotubes. The aim of the modification was to create a conductive network between cell lipid membranes, containing exposed PQQ-dependent alcoholdehydrogenases, and the electrode to facilitate electron transfer in the system. The bioelectrochemical characteristics of modified anodes at various cell/polymer ratios were assessed via current density, power density, polarization curves and impedance spectres. MFCs based on chitosan at a matrix/cell volume ratio of 5:1 produced maximal power characteristics of the system (8.3 μW/cm2) at a minimal resistance (1111 Ohm cm2). Modification of the anode by multiwalled carbon nanotubes led to a slight decrease of internal resistance (down to 1078 Ohm cm2) and to an increase of generated power density up to 10.6 μW/cm2. We explored the possibility of accumulating electric energy from an MFC on a 6,800-μF capacitor via a boost converter. Generated voltage was increased from 0.3 V up to 3.2 V. Accumulated energy was used to power a Clark-type biosensor and a bluetooth transmitter with three sensors, a miniature electric motor and a light-emitting diode.
REVIEW | doi:10.20944/preprints201802.0070.v1
Subject: Earth Sciences, Environmental Sciences Keywords: microbial sulphide oxidation, corrosion, mine waste and water remediation, biofilm development, inhibition of Acid mine and rock draiange
Online: 8 February 2018 (15:35:56 CET)
Abstract: Measures to counteract AMD generation need to start at the mineral surface, inhibiting mineral-oxidizing, acidophilic microbes. Laboratory and long-term field tests with pyrite-containing mining wastes, where Carbonaceous Phosphate Mining Waste (CPMW) was added, resulted in low acidity, and near neutral drainage. The effect was reproducible, nd confirmed by several independent research groups. This was shown to involve an organic coating, likely a biofilm. The biofilm formation was confirmed when CPMW was added to lignite coal waste with an initial pH of 1. Forty five days after the addition, the coal waste was dominated by heterotrophic microorganisms in biofilms. A review of the scientific literature supports that CPMW has physical and chemical characteristics which are capable of inducing a strong inhibitory effect on sulphide oxidation by forming an organic coating over the mineral surface. CPMW characteristics appear to provide the cornerstone of a new technology for the reduction of sulphide oxidation in mine wastes. An hypothesis for testing this technology is presented which could result in an economical and sustainable approach to mine waste and water management.
ARTICLE | doi:10.20944/preprints202012.0076.v1
Subject: Engineering, Automotive Engineering Keywords: oxygen reduction reaction; multi-functional catalysts for ORR; bioelectrocalysis; biocathodic microbial communities; optimization of catalyst layers and electrode design
Online: 3 December 2020 (09:26:40 CET)
The construction of optimized biological fuel cells requires a cathode which combines the longevity of a microbial catalyst with the power density of an enzymatic catalyst. Laccase secreting fungi were grown directly on the cathode of a biological fuel cell to facilitate the exchange of inactive enzymes with active enzymes with the goal of extending the lifetime of laccase cathodes. Additionally, a functionally graded coating was developed to increase enzyme loading at the cathode. Directly incorporating the laccase producing fungus at the cathode extends the operational lifetime of laccase cathodes while eliminating the need for frequent replenishment of the electrolyte. Additionally, the hybrid microbial-enzymatic cathode addresses the issue of enzyme inactivation by using the natural ability of fungi to exchange inactive laccases at the cathode with active laccases. Finally, enzyme adsorption was increased through the use of a functionally graded coating containing an optimized ratio of titanium dioxide nanoparticles and single walled carbon nanotubes. The hybrid microbial-enzymatic fuel cell combines the higher power density of enzymatic fuel cells with the longevity of microbial fuel cells and demonstrates the feasibility of a self-regenerating fuel cell in which inactive laccases are continuously exchanged with active laccases.
ARTICLE | doi:10.20944/preprints202208.0150.v1
Subject: Biology, Agricultural Sciences & Agronomy Keywords: black pepper; Bacillus veleznesis; root-knot nematodes; antinematodes compounds; organic wastes; microbial fermentation; thymine; hexahydropyrrolo [1,2-a]pyrazine-1,4-dione
Online: 8 August 2022 (10:30:28 CEST)
Bacillus veleznesis RB.EK7 was recently found as a potent rhizobacterial strain for effective management of black pepper root-knot nematodes. This work aimed to produce, purify, and elucidate the chemical structures of antinematode compounds (ANCs). Concerning cost-effectiveness and environmental issues, this study used organic wastes for the bioproduction of ANCs. Among various substrates, shrimp shells powder was the most suitable carbon/nitrogen source to produce ANCs. The fermentation process for enhancement of antinematode activity was investigated. The targeting ANCs were purified from the fermented culture broth, and their structures were elucidated. Two active compounds were thymine (1) and hexahydropyrrolo [1,2-a]pyrazine-1,4-dione (2). Notably, for the first time, these purified compounds showed potential and moderate anti- J2 nematodes and anti-eggs hatching, respectively. The docking study results indicated that the potent antinematode effect of these compounds may be possibly due to the inhibition of the targeting enzyme acetylcholinesterase. The data of this work suggest that organic waste SSP can be potentially reused for the production of thymine and hexahydropyrrolo [1,2-a] pyrazine-1,4-dione with promising use for the management of black pepper nematodes.
ARTICLE | doi:10.20944/preprints202205.0103.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: chemical oxygen demand (COD); zero liquid discharge (ZLED); poly-aluminum chloride; chemi-cal-coagulation; jar-test; Microbial Fuel Cell (MFC)
Online: 9 May 2022 (05:48:07 CEST)
This study develops into the application of a combined MFC unit with chemical coagulation for total treatment of inert contaminants in complex substrates. Microbial Fuel Cell (MFC) technology converts chemical energy in the form of organic matter, into bioelectricity in an environmentally friendly and effi-cient manner, reducing carbon emissions and increasing bioenergy production. An evaluation of a la-boratory scale chemical coagulation using an aluminum and poly-based coagulant on how effective it can remove bulk impurities such as particulate COD and turbidity to obtain the purest and most cost-effectively treated wastewater using a jar test is being conducted in this current study. This study aims to find the most effective treatment technologies for wastewater recovery in breweries in order to achieve zero liquid effluent discharge (ZLED). The preliminary results showed that adding a modest amount of poly and a 50 % alum alone treatment improved COD, color, and turbidity reduction. The turbidity removal efficiency achieved after chemical coagulation treatment was 90.50 % and 59.36 % COD removal, demonstrating the benefits of adopting an alum/poly based technique. To determine ZLED, this study clearly advised a combined treatment technique, specifically the MFC-flocculator unit for efficient organics and inorganics removal.