TECHNICAL NOTE | doi:10.20944/preprints202111.0488.v1
Subject: Life Sciences, Microbiology Keywords: spheroid; tumour spheroid; mounting; clearing; microscopy; structure; confocal
Online: 25 November 2021 (16:15:34 CET)
Tumour spheroids are fast becoming commonplace in basic cancer research and drug development. Obtaining high-quality data relating to the inner structure of spheroids is important for analysis, yet existing techniques often use equipment that is not commonly available, are expensive, laborious, cause significant size distortion, or are limited to relatively small spheroids. We present a high-throughput method of mounting, clearing, and imaging tumour spheroids that causes minimal size distortion. Spheroids are mounted in an agarose gel to prevent movement, cleared using a solution prepared from commonly available materials, and imaged using confocal microscopy. We find that our method yields high quality two- and three-dimensional images that provide information about the inner structure of spheroids.
ARTICLE | doi:10.20944/preprints202111.0474.v1
Subject: Life Sciences, Microbiology Keywords: probiotic; Enterococcus faecium; antimicrobial resistance; environmental change
Online: 25 November 2021 (12:49:29 CET)
In two sequential replicates (n=90 and n=96 feedlot finisher cattle, respectively) we measured the impact of an Enterococcus faecium-based probiotic (DFM) and an altered feedlot pen environment on antimicrobial resistance among fecal enterococci in cattle fed (or, not fed) the macrolide tylosin. Diluted fecal samples were spiral-plated on plain and antibiotic-supplemented m-Enterococcus agar. In the first replicate, tylosin significantly (p<0.05) increased the relative quantity of erythromycin-resistant enterococci. This effect was diminished in cattle fed the DFM in conjunction with tylosin. A similar observed effect was not statistically significant (P > 0.05) in the second replicate. Isolates were speciated and resistance phenotypes were obtained for E. faecium and E. hirae. E. faecium isolates were whole-genome sequenced, which yielded sequence types (ST), resistance genes and phylogeny. Samples of the DFM were sequenced and found to contain E. faecium ST296, which was not present on Day 0 of either replicate. This DFM sequence type was found in fecal samples after Day 0, the majority of which were isolated from cattle in one of the DFM-fed pens. Increased prevalence of ST296 occurred with a concomitant decrease in ST240; of importance, the latter typically harbored both ermB and tet(M) genes.
Tue, 23 November 2021
ARTICLE | doi:10.20944/preprints202111.0426.v1
Subject: Life Sciences, Microbiology Keywords: Bacillus anthracis; anthrax; outbreak; phylogenetics; detection assay
Online: 23 November 2021 (14:44:33 CET)
The zoonotic disease anthrax caused by the endospore-forming bacterium Bacillus anthracis is very rare in Germany. In the state of Bavaria, the last case occurred in July of 2009 resulting in four dead cows. In August of 2021, the disease reemerged after heavy rains, killing one gestating cow. Notably, both outbreaks affected the same pasture, suggesting a close epidemiological connection. B. anthracis could be grown from blood culture and the presence of both virulence plasmids (pXO1 and pXO2) were confirmed by PCR. Also, recently developed diagnostic tools enabled rapid detection of B. anthracis cells and nucleic acids directly in clinical samples. The complete genome of the strain isolated from blood, designated BF-5, was DNA-sequenced and phylogenetically grouped within the B.Br.CNEVA clade that is typical for European B. anthracis strains. The genome was almost identical to BF-1, the isolate of 2009, separated only by three single nucleotide polymorphisms on the chromosome, one on plasmid pXO2 and three indel-regions. Further, B. anthracis DNA was detected by PCR from soil-samples taken from spots, where the cow had fallen onto the pasture. New tools based on phage receptor binding proteins enabled the microscopic detection and isolation of B. anthracis directly from soil-samples. These environmental isolates were genotyped and found to be SNP-identical to BF-1. Therefore, it seems that the BF-5 genotype is currently the prevalent one at the affected premises. The contaminated area was subsequently disinfected with formaldehyde.
Mon, 22 November 2021
ARTICLE | doi:10.20944/preprints202111.0376.v1
Subject: Life Sciences, Microbiology Keywords: Mast cells; Leishmania mexicana; sand fly salivary proteins; sexual hormones
Online: 22 November 2021 (10:51:24 CET)
Mast cells (MCs) play a crucial role during infections with Leishmania, that is transmitted through the bite of an infected sand fly that injects saliva together with the parasite. Sand fly saliva is a complex fluid that modulates the host immune response. In addition, hormonal factors modulate the host immune response, impacting the susceptibility to infections. Thus, to assess the impact of androgens and salivary proteins of sand fly vectors on the mast cell (MC) response to Leishmania infections, we infected orchiectomized male mice with the parasite in the presence or absence of sand fly salivary proteins and analyzed the inflammatory response of MCs. Our results showed a differential MC response to the parasite and to vector salivary proteins in mice deprived of gonadal hormones, as compared to sham-operated mice. Orchidectomy induced a different pattern of activation in MC of animals infected with Leishmania and vector-salivary proteins. Our results show that during Leishmania infection, androgens modulate the innate immunity response against the parasite and salivary proteins of the sand fly vector.
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.
Fri, 19 November 2021
REVIEW | doi:10.20944/preprints202111.0358.v1
Subject: Life Sciences, Microbiology Keywords: multidrug-resistant (MDR); Nanotechnology; Antimicrobial
Online: 19 November 2021 (14:31:33 CET)
The global spread of multidrug-resistant (MDR) microbial infections is currently one of the most severe risks to global public health, with 10 million fatalities expected by 2050 unless action is taken. Nanotechnology has revolutionized science and medicine. The reliance on nanotechnology is growing. Nanoparticles have distinct properties that improve biological, chemical, and physical properties studied for various uses. A significant area of attention in the synthesis of nanoscale modulators is the utilization of crude formulations, retro-synthesized, and pure chemicals, mainly from herbal sources, with fewer adverse effects. Green chemistry has devised a tangential technique for synthesizing metals and metal oxides to produce nanoparticles. Plant extracts (leaves, stems, and shoots) and microorganisms (bacteria, fungus, and yeast) are used as reducing intermediates to make nanoparticles. Studies in microbiology have shown that nanoparticles kill bacteria, fungi, viruses, and protozoa. These green nanoparticles contain antibacterial, antifungal, and anti-inflammatory effects. Most nanoparticles have high antibacterial properties, indicating they may be used to combat diseases and biological contaminants. These nanoparticles have antibacterial action against pathogenic microorganisms that cause serious illnesses, including multidrug-resistant pathogens. The current research will pave the way for future applications and improved methods for producing nanoparticles, paving the way for an innovative route in nano-life sciences with widespread recognition.
ARTICLE | doi:10.20944/preprints202111.0347.v1
Online: 19 November 2021 (11:29:21 CET)
Monascus pigments (MPs) have been used as food colorants for several centuries in Asian countries and nowadays in the whole world via Asian catering. The MPs biosynthetic pathway has been well-illustrated, however, the functions of a few genes including mrpigH in the MPs gene cluster of M. ruber M7 are still unclear. In current study, mrpigH was disrupted in Δmrlig4ΔmrpyrG, a highly efficient gene modification system, using mrpyrG as a selection marker, and ΔmrpigHΔmrlig4ΔmrpyrG::mrpyrG and ΔmrpigHΔmrlig4ΔmrpyrG have been obtained. Subsequently, their morphologies, biomasses, MPs and citrinin (CIT) production were analyzed, respectively. These results have revealed that the deletion of mrpigH has significant effects on the morphology and growth of M. ruber M7. Moreover, compared with M. ruber M7, the yields of MPs and CIT were drastically increased and decreased in mrpigH mutants, respectively.
Tue, 16 November 2021
ARTICLE | doi:10.20944/preprints202111.0287.v1
Subject: Life Sciences, Microbiology Keywords: Excretory-secretory products; Angiostrongylus cantonensis; Astrocytes; Benzaldehydes; endoplasmic reticulum stress; oxidative stress
Online: 16 November 2021 (11:34:13 CET)
Excretory-secretory products (ESPs) are the main research targets for investigating the hosts and helminths interaction. Parasitic worms can migrate to parasitic sites and avoid the host immune response by secreting this product. Angiostrongylus cantonensisis an important food-borne zoonotic parasite that causes severe neuropathological damage and symptoms, including eosinophilic meningitis or meningoencephalitis in humans. Benzaldehydes are organic compounds composed of a benzene ring and formyl substituents. This compound has anti-inflammatory and antioxidation properties. Previous studies showed that 3-hydroxybenzaldehyde (3-HBA) and 4-hydroxybenzaldehyde (4-HBA) can reduce apoptosis in A. cantonensis ESPs treated astrocytes. These results on the protective effect underlying benzaldehyde have primarily focused on cell survival. The study was designed to investigate the molecular mechanisms of endoplasmic reticulum stress (ER stress) and oxidative stress in astrocytes in A. cantonensis ESPs treated astrocytes and to evaluate the therapeutic consequent of 3-HBA and 4-HBA. First, we initially established the RNA-seq dataset in each group, including Normal, ESPs, ESPs+3-HBA, and ESPs+4-HBA. We also found that benzaldehyde (3-HBA and 4-HBA) can stimulate astrocytes to express ER stress-related molecules after ESP treatment. The level of oxidative stress could also be decreased in astrocytes by elevating antioxidant activity and reducing ROS generation. These results suggested that benzaldehyde may be a potential therapeutic compound for human angiostrongyliasis to support brain cell survival by inducing the expression levels of ER stress- and oxidative stress-related pathway.
CASE REPORT | doi:10.20944/preprints202111.0284.v1
Subject: Life Sciences, Microbiology Keywords: acute acalculous cholecystitis; Orientia tsutsgugamushi; scrub typhus; eschar; Epstein-Barr virus; re-activation; clinical manifestation; Maldives
Online: 16 November 2021 (09:34:22 CET)
Scrub typhus is a neglected tropical disease predominantly occurring in Asia. The causative agent is a bacterium transmitted by the larval stage of mites found in rural vegetation in endemic regions. Cases of scrub typhus frequently present as acute undifferentiated febrile illness, and without early diagnosis and treatment, the disease can develop fatal complications. We retrospectively reviewed de-identified data from a 23-year-old woman who presented to an emergency department with complaints of worsening abdominal pain. On presentation, she appeared jaundiced and toxic-looking. Other positive findings on abdominal examination were a positive Murphey’s sign, abdominal guarding and hepatosplenomegaly. Magnetic resonance cholangiopancreatography demonstrated acalculous cholecystitis. Additional findings included eschar on the medial aspect of the left thigh with inguinal regional lymphadenopathy. Further, positive results were obtained for immunoglobulins M and G, confirming scrub typhus. Workups for other infectious causes of acute acalculous cholecystitis detected human herpesvirus 4 (Epstein-Barr virus). Whether that represented acute infection or re-activation of the Epstein-Barr virus could not be determined. As other reports have described acute acalculous cholecystitis in adult scrub typhus patients, we recommend doxycycline to treat acute acalculous cholecystitis in endemic regions while awaiting serological confirmation.
Thu, 11 November 2021
ARTICLE | doi:10.20944/preprints202111.0212.v1
Subject: Life Sciences, Microbiology Keywords: oats; fusarium sambucinum species complex; deoxynivalenol; nivalenol; mycotoxin
Online: 11 November 2021 (13:05:00 CET)
Oats are a nutrient rich cereal used for animal feed and growing in human consumption. This cereal can be affected by Fusarium spp., causing the disease Fusarium Head Blight. This disease is caused mainly by species within the Fusarium graminearum species complex, and are also responsible for producing mycotoxins that are harmful to humans and animals. This study aimed to investigate fungal diversity in Brazilian oat samples, focusing on the Fusarium sambucinum species complex and the presence of type B trichothecenes (deoxynivalenol and its derivatives, and nivalenol) from two different regions; Paraná (PR) and Rio Grande do Sul (RS). The isolated fungi from oat grains were identified as species from the genera: Fusarium, Phoma and Alternaria. The majority of Fusarium isolates belonged to the Fusarium sambucinum species complex; identified as F. graminearum s.s., F. meridionale and F. poae. In the RS region, F. poae was the most frequent fungus, while FGSC was the most frequent in the PR region. The majority of F. graminearum s.s. isolates were of the 15-ADON genotype, while some 3-ADON genotypes were identified; however, F. meridionale and F. poae were all of the NIV genotype. Mycotoxin analysis revealed that 92% and 100% of the samples from PR and RS were contaminated with type B trichothecenes, respectively. The oats from PR were predominantly contaminated with DON, whereas NIV was predominant in oats from RS. Analysis showed that 24% of the samples were contaminated with DON at levels higher than Brazilian regulations. Co-contamination of DON, its derivatives and NIV was observed in 84% and 57.7% of the samples from PR and RS, respectively. The results provide new information on Fusarium contamination in Brazilian oats, highlighting the importance for further studies on mycotoxins.
Tue, 9 November 2021
ARTICLE | doi:10.20944/preprints202111.0176.v1
Subject: Life Sciences, Microbiology Keywords: whole genome sequencing; antibiotic resistance; Salmonella Enteritidis; Salmonella Typhimurium; Salmonella Bovismorbificans; colistin resistance; mcr-1; mcr-9
Online: 9 November 2021 (13:46:05 CET)
Polymyxin resistance, determined by mcr genes located on plasmid DNA, currently pose a high epidemiological threat. Non-typhoid Salmonella (NTS) are one of the key pathogens causing diarrheal diseases. Here, we report the isolation and whole genome sequencing of multidrug colistin-resistant/susceptible isolates of non-typhoid Salmonella enterica serovars carries mcr genes. Non-typhoid strains of Salmonella enterica subsp. enterica were isolated during microbiological monitoring of the environment, food, and diarrheal disease patients between 2018 and 2020 in Russia (n=586). mcr-1 genes were detected using a previously developed qPCR assay and whole genome sequencing of mcr positive isolates was performed by both short-read (Illumina) and long-read (Oxford Nanopore) approaches. Three colistin-resistant isolates including two isolates of S. Enteritidis and one isolate of S. Bovismorbificans carried the mcr-1.1 gene located on IncX4 and IncI2 conjugative plasmids, respectively. The phenotypically colistin-susceptible isolate of S. Typhimurium carried a mcr-9 gene on plasmid IncHI2. In conclusion, we present the first three cases of mcr gene carrying NTS isolates detected in Russia with both outbreak and sporadic epidemiological background.
Mon, 8 November 2021
REVIEW | doi:10.20944/preprints202111.0157.v1
Subject: Life Sciences, Microbiology Keywords: Microbiome; Cattle; Johne’s disease; Dysbiosis; Mastitis
Online: 8 November 2021 (15:17:16 CET)
: Cattle farming is an ancient practice, with roots in the early Neolithic era that has retained its status in the food industry today, with global beef market revenue amounting to $385.7B, as of 2018. Hence, cattle maintenance is naturally essential to cater to nutritional requirements of modern civilization. This extensive review aims to provide a holistic overview of cattle microbiome, analysing the native microbial composition within respiratory tract, gastrointestinal tract, reproductive tract, and skin. The dysbiosis associated with various diseases such as bovine respiratory disease, bovine digital dermatitis, mastitis, Johne's disease, uterine diseases (metritis and endometritis) and metabolic disorders (ruminal acidosis and ketosis) has been discussed. Moreover, various non-antibiotic microbial therapies including phage therapy, prebiotics and probiotics have been examined as potential means to reduce disease-associated dysbiosis. In general, this review highlights the importance of the microbiome in maintenance of health in cattle and its potential in alleviating bovine diseases, with an aim to enhance cattle health and production.
Wed, 3 November 2021
ARTICLE | doi:10.20944/preprints202111.0058.v1
Subject: Life Sciences, Microbiology Keywords: ozone; detrimental effect; pathogenic bacteria; antimicrobial resistance; ROS; Acinetobacter baumannii; Pseudomonas aeruginosa
Online: 3 November 2021 (07:55:57 CET)
(1) Background: Disinfection of medical devices designed for clinical use associated or not with the growing area of tissue engineering is an urgent need. However, traditional disinfection methods are not always suitable for some biomaterials, especially those sensitive to chemical, thermal, or radiation. Therefore, the objective of this study was to evaluate the minimal concentration of ozone gas (O3) necessary to control and kill a set of sensitive or multi-resistant Gram-positive and Gram-negative bacteria. The cell viability, membrane permeability, and the levels of reactive intracellular oxygen (ROS) species were also investigated; (2) Material and Methods: Four standard strains and a clinical MDR strain were exposed to low doses of ozone at different concentrations and times. Bacterial inactivation (cultivability, membrane damage) was investigated using colony counts, resazurin as a metabolic indicator, and propidium iodide (PI). A fluorescent probe (H2DCFDA) was used for the ROS analyses; (3) Results: No reduction in the count colony was detected after O3 exposure, compared to the control group. However, the cell viability of E. coli (30%), P. aeruginosa (25%), and A. baumannii (15%) was reduced considerably. The bacterial membrane of all strains was not affected by O3 but presented a significant increase of ROS in E. coli (90 ± 14%), P. aeruginosa (62.5 ± 19%), and A. baumanni (52.6 ± 5%); (4) Conclusion: Low doses of ozone were able to interfere in the cell viability of most strains studied, and although it does not cause damage to the bacterial membrane, increased levels of reactive ROS are responsible for causing a detrimental effect in the lipids, proteins, and DNA metabolism.
Tue, 2 November 2021
COMMUNICATION | doi:10.20944/preprints202111.0055.v1
Subject: Life Sciences, Microbiology Keywords: hosue fly,; falling,; dipping,; antimicrobial,; milk,; water
Online: 2 November 2021 (22:48:42 CET)
Background: The study describes the comparison of different microbial load results of natural falling and dipping of the house fly (Musca domestica) in water and milk to investigate the possibilities of preventing the effect of the transferred pathogens from the house fly to our sources by pointing out the existence of antimicrobial factors within the house fly. Methods: Samples of house fly were collected from Jeddah and Makkah (Makkah region) and were directly transferred to the laboratory. Each house fly was packed in sterile test tubes. Each tube was opened oppositely to a larger test tube containing 10 ml of sterile tap water, and sterile water at pH 4.0 in other similar series of treatments to represent the reactions of stomach fluids. Later, the house flies were left for 20 seconds after reaching the water surface, and then cultured on different microbial media to evaluate the microbial load of the natural falling of the house fly. To evaluate the complete dipping of house flies in the water, two methods were tested by one complete dip for the flies for 20 seconds, and three times complete dipping for 20 seconds in water before evaluating the microbial load. The same methods were achieved on milk in a series of experiments and the microbial load was evaluated after the incubation at room temperature for three hours. Results: It was found that dipping treatments of house flies gave lower microbial contamination in water at pH 4.0 than neutral pH. The lower microbial load was also observed when dipping the house flies three times in water as compared to once dipping and natural falling treatments. It was also found that the complete dipping of house flies’ treatments in milk will reduce the microbial contamination as compared to natural falling treatments. Conclusion: The observed results support the presence of antimicrobial factors on the house fly.
Mon, 1 November 2021
ARTICLE | doi:10.20944/preprints202111.0014.v1
Subject: Life Sciences, Microbiology Keywords: aflatoxin M1; milk; dairy products; risk assessment; children
Online: 1 November 2021 (12:26:43 CET)
The present study was conducted to estimate the exposure and risk characterization of the children population of Serbia to Aflatoxin M1 (AFM1) from milk and milk-based food. A total of 3404 samples comprising of milk and different milk-based food samples were collected from various regions of Serbia from 2017 to 2019. Evaluation of the AFM1 exposure was carried out using the deterministic method, whereas risk characterization was evaluated with the calculation of the Margin of Exposure (MOE) and the risk of Hepatocellular Carcinoma (HCC). Detection rates for AFM1 in milk and milk-based food samples ranged between 2% and 79%, with the highest incidence (79%) and mean level (22.34 0,018 ng kg-1) of AFM1 was detected in pasteurized and UHT milk. According to the three consumption estimates, the values of EDI were higher for toddlers as compared with children. Children aged 1–3 years had the highest risk of exposure to AFM1 in milk, with an estimated daily intake of 0.164 and 0.193 ng kg-1 bw day-1 using a lower bound (LB) and the upper bound (UB) exposure scenarios, respectively. Such difference could result from the higher consumption versus weight. Based on the EDI found in this study, the risk of AFM1 due to consumption of milk and milk-based food was low since MOE values obtained were 10000. In addition, the risk of HCC cases/year/105 individuals of different age groups showed that the value of HCC using potency estimates of 0.0017 (mean) was maximum (0.00034) in the age group 1–3 years which indicates no health risk for the evaluated groups. The present study revealed the importance of controlling and preventing AFM1 contamination in milk through continuous monitoring and regular inspection to reduce the risk of AFM1 exposure, especially in children.
Thu, 21 October 2021
ARTICLE | doi:10.20944/preprints202110.0308.v1
Subject: Life Sciences, Microbiology Keywords: Salmonella newington; ɛ34 phage; Lipopolysaccharides; Antibacterial
Online: 21 October 2021 (12:47:13 CEST)
Salmonella can cause acute and chronic infections in humans. Salmonella species are known to cause food poisoning and other diseases in developing countries. Their role in the pathogenesis of these diseases has received increased international attention. Despite numerous advances in sanitation, they still can infect humans and cause outbreaks in developed countries. For example, Salmonella causes about 1.2 million illnesses in the US each year with over 450 deaths. Additionally, Salmonella outbreaks cause significant losses to chicken producers globally. The Salmonella species is also prone to acquiring resistance to various classes of antibiotics. Hence, the need for a paradigm shift from antibiotics to bacteriophages to manage, control and treat bacterial infections. The ɛ34 phage belongs to Podoviruses and categorized into the P22-like phages. The P22-like phages include ɛ34, ES18, P22, ST104, and ST64T. In this work, we investigated the antibacterial property of ɛ34 phage tailspike protein against Salmonella newington (S. newington). We demonstrate here that, the phage’s tailspike protein enzymatic property as a LPS hydrolase synergizes with Vero Cell culture supernatant in killing S. newington. Using decellularized cartilage scaffold as an ex vivo tissue model, the ɛ34 TSP protected the scaffold from S. newington biofilm formation. Computational analysis of the ɛ34 TSP interaction with membrane proteins of S. newington demonstrated a higher probability (0.7318) of binding to ompA of S. newington, and when docked to ompA extracellular component, it produced a high free energy of -11.3kcal/mol. We also demonstrate the resistance/sensitivity of the tailspike to the digestive enzyme trypsin. The data obtained in this work indicates that the trypsin resistant tailspike protein of Ɛ34 phage can be formulated as a novel antibacterial agent against S. newington.
Tue, 19 October 2021
REVIEW | doi:10.20944/preprints202107.0044.v3
Online: 19 October 2021 (13:23:01 CEST)
Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis (Mtb), with 10.4 million new cases per year reported in the human population. Recent studies on the Mtb transcriptome have revealed the abundance of noncoding RNAs expressed at various phases of mycobacteria growth, in culture, in infected mammalian cells and in patients. Among these noncoding RNAs are both small RNAs (sRNAs) between 50-350 nts in length and smaller RNAs (sncRNA) <50 nts. In this review, we provide an up-to-date synopsis of the identification, designation, and function of these Mtb-encoded sRNAs and sncRNAs. The methodological advances including RNA sequencing strategies, small RNA antagonists and locked nucleic acid sequence specific RNA probes advancing the studies on these small RNA are described. Initial insights into the regulation of the small RNA expression and putative processing enzymes required for their synthesis and function are discussed. There are many open questions remaining about the biological and pathogenic roles of these small non-coding RNAs, and potential research directions needed to define the role of these mycobacterial noncoding RNAs summarized.
ARTICLE | doi:10.20944/preprints202110.0273.v1
Subject: Life Sciences, Microbiology Keywords: 18S; Cryptosporidium; dairy cattle; gp60; genotyping; prevalence
Online: 19 October 2021 (11:54:33 CEST)
Cryptosporidium is comprised an apicomplexan parasitic protist, which infects a wide range of hosts, causing cryptosporidiosis. In cattle farms, the incidence of cryptosporidiosis results in high mortality in calves leading to considerable economic loss in the livestock industry. Infected animals may also act as a major reservoir of Cryptosporidium spp., in particular C. parvum, the most common cause of cryptosporidiosis in calves. This poses a significant risk to other farms via breeding centres, to trading of livestock and to human health. This study, funded by the Interreg-2-seas programme, is a part of a global project aimed at strategies to tackle cryptosporidiosis. To reach this target, it was essential to determine whether prevalence was dependent on the studied countries or if the issue was borderless. Indeed, C. parvum occurrence was assessed across dairy farms in certain regions of Belgium, France and the Netherlands. At the same time, the animal-to-animal transmission of the circulating C. parvum subtypes was studied. To accomplish this, 1084 faecal samples, corresponding to 57 dairy-farms from all three countries, were analysed. Well-established protocols amplifying the 18S rDNA and gp60 genes fragments, followed by DNA sequencing, were used for the detection and subtyping C. parvum; the DNA sequences obtained were further characterised using a combination of bioinformatics and phylogenetics methods. Our results show 25.7%, 24.9% and 20.8% prevalence of Cryptosporidium spp. in Belgium, France and the Netherlands respectively. Overall, 93% of the farms were Cryptosporidium positive. The gp60 subtyping demonstrated a significant number of the C. parvum positives belonged to the IIa allelic family, which has been also detected in humans. Consequently, this study highlights how widespread is C. parvum in dairy farms and endorses cattle as a major carrier of zoonotic C. parvum subtypes, which subsequently pose a significant threat to human health.
ARTICLE | doi:10.20944/preprints202110.0268.v1
Subject: Life Sciences, Microbiology Keywords: P. polymyxa; bioactive peptides; volatiles; MALDI-TOF mass spectrometry; GC-MS
Online: 19 October 2021 (10:29:01 CEST)
Paenibacilli are efficient producers of potent agents against bacterial and fungal pathogens, which are of great interest both for therapeutic applications in medicine as well as in agrobiotechnol-ogy. Lipopeptides produced by such organisms play a major role in their inactivation potential. In this work we investigated two lipopeptide complexes, the fusaricidins and the polymyxins, produced by Paenibacillus polymyxa strains DSM 32871 and M1 by MALDI-TOF mass spectrometry. The fusaricidins show potent antifungal activities and are distinguished by an unusual variabil-ity. For strain DSM 32871 we identified numerous yet unknown variants mass spectrometrically. DSM 32871 produces polymyxins of type E (colistins), while M1 forms polymyxins P. For both strains novel, but not yet completely characterized polymyxin species were detected, which pos-sibly are glycosylated. These compounds may be of interest therapeutically, because polymyxins attain increasing attention as last-resort antibiotics against multiresistant pathogenic Gram-negative bacteria. In addition, the volatilomes of DSM 32781 and M1 were investigated with a GC-MS approach using different cultivation media. Production of volatile organic com-pounds (VOCs) was strain and medium dependent. In particular, strain M1 manifested as an effi-cient VOC-producer that exhibited formation of 25 volatiles in total. A characteristic feature of Paenibacilli is the formation of volatile pyrazine derivatives.
Wed, 13 October 2021
REVIEW | doi:10.20944/preprints202110.0194.v1
Subject: Life Sciences, Microbiology Keywords: AMF; Vegetable production; plant pests; plant diseases
Online: 13 October 2021 (10:30:06 CEST)
AMF (Arbuscular Mychorhizal Fungi) are very well known due to their importance in promoting growth and developments of plants especially vegetables. These fungi can be grown easily, stored and multiplied with simple means, also the application of these fungi is generally on the layer of the soil or near the roots in the inner layers of the soils. The growth of the amf fungi is very easy and they are highly adjustable to any soil and environmental conditions. In this review our main focus is on the use of amf for production of vegetables and also the effect of amf against insects and pests. The amf is known to reduce several symptoms caused by different insect pests and also plant diseases thereby promoting healthy growth of the plants. Also use of this amf will increase the uptake of nutrient from the soils through symbiotic relationships between plants and fungi. The uptake of important minerals which are drawn from deeper layers of soils is observed with the help pf amf. This study reveals the benefits of the use of amf under severe disease and pest incidences thereby known as an alternate for harmful chemical pesticides and fungicides.
Thu, 7 October 2021
ARTICLE | doi:10.20944/preprints202110.0117.v1
Online: 7 October 2021 (11:00:12 CEST)
Leishmanial skin lesions are characterized by inflammatory hypoxia alongside the activation of hypoxia inducible factors, HIF-1a and HIF-2a, and subsequent expression of the HIF-a target VEGF-A during Leishmania major infection. However, the factors responsible for HIF-a activation are not known. We hypothesize hypoxia and pro-inflammatory stimuli contribute to HIF-a activation during infection. RNASeq on leishmanial lesions found transcripts associated with HIF-1a signaling are induced. To determine whether hypoxia contributes to HIF-a activation, we followed the fate of myeloid cells infiltrating from the blood and into hypoxic lesions. Recruited myeloid cells experience hypoxia when they enter inflamed lesions, and the length of time in lesions increases their hypoxic signature. To determine whether pro-inflammatory stimuli in the inflamed tissue can also influence HIF-a activation, we subjected macrophages to various pro-inflammatory stimuli and measured VEGF-A. While parasites alone did not induce VEGF-A, and pro-inflammatory stimuli only modestly induce VEGF-A, HIF- stabilization increases VEGF-A during infection. HIF-a stabilization does not impact parasite entry, growth or killing. Alternatively, the absence of ARNT/HIF- signaling enhances parasite internalization. Altogether, these findings suggest HIF-a is active during infection, and while macrophage HIF-a activation promotes lymphatic remodeling through VEGF-A production, HIF-a activation does not impact parasite internalization or control.
Thu, 30 September 2021
REVIEW | doi:10.20944/preprints202109.0516.v1
Subject: Life Sciences, Microbiology Keywords: Tuberculosis; Mycobacterium tuberculosis; diabetes; hyperglycemia; dyslipidemia; cholesterol; triglycerides
Online: 30 September 2021 (14:01:44 CEST)
Diabetes is a major risk factor for tuberculosis (TB). Diabetes increases the risk of progression from latent tuberculosis infection (LTBI) to active pulmonary TB and TB patients with diabetes are at greater risk of more severe disease and adverse TB treatment outcomes compared to TB patients without co-morbidities. Diabetes is a complex disease characterized not only by hyperglycemia but also various forms of dyslipidemia. However, the relative contribution of these underlying metabolic factors to increased susceptibility to TB are poorly understood. This review summarizes our current knowledge on epidemiology and clinical manifestation of TB and diabetes comorbidity. We subsequently dissect the relative contribution of body mass index, hyperglycemia, elevated cholesterol and triglycerides on TB disease severity and treatment outcomes. Lastly, we discuss the impact of selected glucose and cholesterol lowering treatments frequently used in the management of diabetes on TB treatment outcomes.
Wed, 29 September 2021
REVIEW | doi:10.20944/preprints202109.0491.v1
Subject: Life Sciences, Microbiology Keywords: Tuberculosis; Mycobacterium; Diagnostics; Drug Discovery; Antibiotics; Antimicrobial Re-sistance; Microfluidics; Single-Cell Analysis; Bioengineered Models
Online: 29 September 2021 (11:34:04 CEST)
Tuberculosis (TB) remains a global healthcare crisis with an estimated 10 million new cases and 1.4 million deaths per year TB is caused by infection with the major human pathogen Mycobacte-rium tuberculosis, which is difficult to rapidly diagnose and treat. There is an urgent need for new methods of diagnosis, sufficient in vitro models which capably mimic all physiological condi-tions of the infection, and high-throughput drug screening platforms. Microfluidic-based tech-niques provide single-cell analysis which reduces experimental time, the cost of reagents, and have been extremely useful for gaining insight into monitoring microorganisms. This review out-lines the field of microfluidics and discusses the use of this novel technique so far in M. tuberculo-sis diagnostics, research methods, and drug discovery platforms. The practices of microfluidics have promising future applications for diagnosing and treating TB.
Mon, 27 September 2021
COMMUNICATION | doi:10.20944/preprints202109.0457.v1
Subject: Life Sciences, Microbiology Keywords: counter-selection; unnatural amino acids; pyrrolysyl tRNA synthetase; genetic code expansion; sence codon reassignment; plasmid curing
Online: 27 September 2021 (17:09:00 CEST)
A protocol was designed for plasmid curing using a novel counter-selectable marker, named pylSZK-pylT, in Escherichia coli. The pylSZK-pylT marker consists of the archaeal pyrrolysyl-tRNA synthetase (PylRS) and its cognate tRNA (tRNApyl) with modification, and incorporates an unnatural amino acid (Uaa), Nε-benzyloxycarbonyl-l-lysine (ZK), at a sense codon in ribosomally synthesized proteins, resulting in bacterial growth inhibition or killing. Plasmid curing is performed by exerting toxicity on pylSZK-pylT located on the target plasmid, and selecting only proliferative bacteria. All tested bacteria obtained using this protocol had lost the target plasmid (64/64), suggesting that plasmid curing was successful. Next, we attempted to exchange plasmids with the identical replication origin and an antibiotic resistance gene without plasmid curing using a modified protocol, assuming substitution of plasmids complementing genomic essential genes. All randomly selected bacteria after screening had only the substitute plasmid and no target plasmid (25/25), suggesting that plasmid exchange was also accomplished. Counter-selectable markers based on PylRS-tRNApyl, such as pylSZK-pylT, may be scalable in application due to their independence from the host genotype, applicability to a wide range of species, and high tunability due to the freedom of choice of target codons and Uaa’s to be incorporated.
Fri, 24 September 2021
REVIEW | doi:10.20944/preprints202109.0416.v1
Subject: Life Sciences, Microbiology Keywords: Malassezia; Chronic diseases; psoriasis; atopic dermatitis; chronic rhinosinusitis; asthma; cystic fibrosis; HIV infection; inflammatory bowel disease; colorectal cancer; neurodegenerative diseases
Online: 24 September 2021 (08:13:07 CEST)
Malassezia are lipid-dependent basidiomycetous yeast of the normal skin microbiome, although Malassezia DNA has been recently detected in other body sites and has been associated with cer-tain chronic human diseases. This new perspective raises many questions. Are these yeasts truly present in the investigated body site or were they contaminated by other body sites, adjacent or not? Does this DNA contamination come from living or dead yeast? If these yeasts are alive, do they belong to the resident mycobiota or are they transient colonizers which are not permanently established within these niches? And, finally, are these yeasts associated with certain chronic diseases or not? In an attempt to shed light on this knowledge gap, we critically re-viewed the 31 published studies focusing on the association of Malassezia spp. with chronic human diseases, including psoriasis, atopic dermatitis (AD), chronic rhinosinusitis (CRS), asthma, cystic fibrosis (CF), HIV infection, inflammatory bowel disease (IBD), colorectal cancer (CRC), and neurodegenerative diseases.
Tue, 21 September 2021
ARTICLE | doi:10.20944/preprints202109.0351.v1
Subject: Life Sciences, Microbiology Keywords: oral microbiota; gut microbiota; networks analysis; ecological niche; newborns
Online: 21 September 2021 (09:13:34 CEST)
The onset and progression of the salivary and gut microbiota, the transmission and the impact of the salivary microbiota on the development of early fecal microbial communities was herein explored. We characterized the microbiota of 82 faecal and 80 salivary samples, collected from 82 healty newborns at birth, 7, 15, 30, 90 and 180 days of life, by 16S rRNA targeted-metagenomics approach. Correlation heat-maps and co-occurrence networks were used to investigate microbial taxa relationship in saliva, gut and between the two ecosystems. In saliva microbiota, Streptococcus and Staphylococcus appeared as early commensals, dominating this ecosystem through the time, while Fusobacterium, Prevotella, Porphyromonas, Granulicatella and Veillonella were late colonizers. anaerobes as Enterobacteriace, Staphylococcus and Streptococcus, were gut microbiota pioneers, followed by the anaerobic Bifidobacterium, Veillonella, Eggerthella and Bacteroides. Streptococcus, Staphylococcus and Veillonella were shared by gut and saliva ecosystems (core microbiota). Early saliva and gut microbiota seem to evolve independently driven by local adaptation strategies, with the only exception for the oral Streptococcus and Veillonella genera, involved in gut microbiota development as seeding species. A more comprehensive knowledge of how oral microbiota may impact pathophysiological conditions of gut microbiota may open new avenues on the design of postbiotics.
Tue, 14 September 2021
SHORT NOTE | doi:10.20944/preprints202109.0241.v1
Subject: Life Sciences, Microbiology Keywords: Bacillus subtilis; bioemulsifier; enrichment; railway soil
Online: 14 September 2021 (12:58:40 CEST)
A novel enrichment combined with a rapid screening method was employed to isolate bioemulsifying strains of Bacillus subtilis. Among a total of twenty isolates from railway soil at six geographically distant sites, ten produced bioemulsifiers for soybean oil and crude oil. Qualitative drop-collapse assays indicated the bioemulsifiers were surfactants.
Mon, 13 September 2021
ARTICLE | doi:10.20944/preprints202109.0210.v1
Subject: Life Sciences, Microbiology Keywords: Parmigiano Reggiano cheese; whey; natural whey starter; ethanol; bioactive peptides; yeasts; Kluyveromyces marxianus; Wickerhamiella pararugosa; Torulaspora delbrueckii.
Online: 13 September 2021 (12:00:03 CEST)
Whey is the main by-product of the dairy industry and contains sugars (lactose) and proteins (especially serum proteins and, at lesser extent, residual caseins), which can be valorized by the fermentative action of yeasts. In the present study, we characterized the spoilage yeast fraction inhabiting natural whey starter (NWS), the undefined starter culture of thermophilic lactic acid bacteria used in Parmigiano Reggiano (PR) cheesemaking, and evaluated thermotolerance, mating type, and the aptitude to produce ethanol and bioactive peptides from whey lactose and proteins, respectively, in a selected pool of strains. We found that PR NWS yeast population consists of other species (Saccharomyces cerevisiae, Wickerhamiella pararugosa, and Torulaspora delbrueckii) in addition to the well-documented Kluyveromyces marxianus, with multiple biotypes scored within each species. Haploid and diploid K. marxianus strains were identified through MAT genotyping, while thermotolerance assay allowed the selection of strains suitable to grow up to 48 °C. In whey fermentation assay, one thermotolerant strain was suitable to release ethanol with yield of 86.5%, while another candidate was able to produce the highest amounts of both ethanol and bioactive peptides with potentially anti-hypertensive function. The present work demonstrated that PR NWS is a reservoir of ethanol and bioactive peptides producer yeasts, which can be exploited to valorize whey, in agreement with the principles of circularity and sustainability.
ARTICLE | doi:10.20944/preprints202109.0193.v1
Subject: Life Sciences, Microbiology Keywords: bioassay; chromatography; folkloric medicine; methicillin-resistant Staphylococcus aureus; Senna alata; spectroscopy
Online: 13 September 2021 (07:21:28 CEST)
Senna alata (Linn) Roxb. plant is widely used to manage various infections in folkloric medicine. Methicillin-resistant Staphylococcus aureus (MRSA) infection continues to be a major global public health problem. This study aims to investigate the bioactive components of S. alata leaves active against MRSA. The leaves of S. alata were sequentially extracted and fractionated using standard methods and screened for activities against MRSA. The diethyl ether active thin layer chromatography (TLC) spot was subjected to infrared (IR) and gas chromatography-mass spectroscopic (GC-MS) studies. The aqueous extract and diethyl ether fraction of S. alata leaves elicited the highest activity against the MRSA. The GC-MS analysis of the fraction produced 15 eluates; only the sub-fraction 13 was effective. The TLC analysis of the sub-fraction 13 revealed three spots; only the second spot produced activity. The GC-MS result of the spot showed six peaks. The spectral results for peak 3 match the data from the IR study suggestive of 9-octadecenoic acid methyl ester. Senna alata leaves possess bioactive compounds closely related to 9-octadecenoic acid methyl ester with potent antibacterial activity against MRSA.
Thu, 2 September 2021
ARTICLE | doi:10.20944/preprints202109.0032.v1
Subject: Life Sciences, Microbiology Keywords: Pseudomonas; Efflux Pumps; Virulence; Evolution; Antibiotic Resistance; Cystic Fibrosis
Online: 2 September 2021 (08:02:02 CEST)
Antibiotic resistant Pseudomonas aeruginosa infections are the primary cause of mortality in people with cystic fibrosis (CF). Yet it has only recently become appreciated that resistance mutations can also increase P. aeruginosa virulence, even in the absence of antibiotics. Moreover, the mechanisms by which resistance mutations increase virulence are poorly understood. In this study we tested the hypothesis that mutations affecting efflux pumps can directly increase P. aeruginosa virulence. Using genetics, physiological assays, and model infections, we show that efflux pump mutations can increase virulence. Mutations of the mexEF efflux pump system increased swarming, rhamnolipid production, and lethality in a mouse infection model, while mutations in mexR that increased expression of the mexAB-oprM efflux system increased virulence during an acute murine lung infection without affecting swarming or rhamnolipid gene expression. Finally, we show that an efflux pump inhibitor, which represents a proposed novel treatment approach for P. aeruginosa, increased rhamnolipid gene expression in a dose-dependent manner. This finding is important because rhamnolipids are key virulence factors involved in dissemination through epithelial barriers and cause neutrophil necrosis. Together, these data show how current and proposed future anti-Pseudomonal treatments may unintentionally make infections worse by increasing virulence. Therefore, treatments that target efflux should be pursued with caution.
Wed, 1 September 2021
ARTICLE | doi:10.20944/preprints202109.0026.v1
Subject: Life Sciences, Microbiology Keywords: Cefotaxime; S. haemolyticus; neonates; sub-MIC; biofilms; short-term evolution
Online: 1 September 2021 (14:39:54 CEST)
Critical care of neonates involves substantial usage of antibiotics and exposure to multidrug resistant (MDR) nosocomial pathogens. These pathogens are often exposed to sub-MIC doses of antibiotics which might result in a range of physiological effects. Therefore, to understand the outcome of sub-inhibitory dosage of antibiotics on Staphylococcus populations, nasal swab specimens were collected from 34 neonates admitted to the Sick Newborn Care Unit between 2017-2018, a total of 41 non-repetitive isolates were included in this study. Staphylococcus haemolyticus was the prevalent species (58.54%) with high non-susceptibility to cefotaxime (CTX) (79.16%), gentamicin (87.50%), and meropenem (54.17%). Biofilm forming abilities of S. haemolyticus isolates in the presence of sub-optimal CTX (30μg/mL), the predominantly prescribed β-lactam antibiotic, were then determined by crystal violet assays and extracellular DNA (eDNA) quantitation. CTX was found to significantly enhance biofilm production among the non-susceptible isolates (p-valueWilcoxin test- 0.000008) with increase in eDNA levels (p-valueWilcoxin test- 0.000004). Additionally, no changes in non-susceptibility were observed among populations of two MDR isolates, JNM56C1 and JNM60C2 after >500 generations of growth in the absence of antibiotic selection in vitro. These findings demonstrate that sub-MIC concentration of CTX induces biofilm formation and short-term non-exposure to antibiotics does not alter non-susceptibility among S. haemolyticus isolates.
Wed, 25 August 2021
ARTICLE | doi:10.20944/preprints202108.0480.v1
Subject: Life Sciences, Microbiology Keywords: Leptospira; bats; Colombia; leptospirosis; species; type; 16S ribosomal gene
Online: 25 August 2021 (09:54:58 CEST)
Leptospirosis is a globally distributed zoonotic disease caused by pathogenic bacteria of the genus Leptospira. This zoonotic disease affects humans, domestic, or wild animals. Colombia is considered an endemic country for leptospirosis; and Antioquia is the second department in Colombia with the highest number of reported leptospirosis cases. Currently, many studies report bats as reservoirs of Leptospira spp. but its prevalence in these mammals is unknown. In the present study we aimed to better understand the role of bats as reservoir hosts of Leptospira species and to evaluate the genetic diversity of circulating Leptospira species in Antioquia-Colombia. We captured 206 bats in the municipalities of Chigorodó (43 bats), Carepa (43 bats), Apartadó (39 bats), Turbo (40 bats), and Necoclí (41 bats) in the Urabá region (Antioquia-Colombia). Twenty bats were positive for Leptospira spp. infection (20/206 - 9,70%) and the species of infected bats were Carollia perspicillata, Dermatura rava, Glossophaga soricina, Molossus molossus, Artibeus planirostris, and Uroderma convexum. These species have different feeding strategies such as frugivorous, insectivores, and nectarivores. The infecting Leptospira species identified were Leptospira borgpetersenii (3/20 – 15%), Leptospira alexanderi (2/20 – 10%), Leptospira noguchii (6/20 – 30%), Leptospira interrogans (3/2 – 15%), and Leptospira kirschneri (6/20 – 30%). The results of this research show the importance of bats in the epidemiology, ecology and evolution of Leptospira in this host-pathogen association. This is the first step in deciphering the role played by bats in the epidemiology of human leptospirosis in the endemic region of Uraba (Antioquia-Colombia).
Mon, 23 August 2021
ARTICLE | doi:10.20944/preprints202108.0451.v1
Subject: Life Sciences, Microbiology Keywords: Staphylococcus aureus; antibiotic resistance; biofilms; antimicrobial peptides; ciprofloxacin; combined effect
Online: 23 August 2021 (14:21:08 CEST)
Staphylococcus aureus can develop resistance by mutation, tranfection or biofilm formation. Resistance was induced in S. aureus by growth in sub-inhibitory concentrations of ciprofloxacin for 30 days. The ability of the antimicrobials to disrupt biofilms was determined using crystal violet and live/dead staining. Effects on the cell membranes of biofilm cells was evaluated by measuring release of dyes and ATP and nucleic acids. S. aureus did not develop resistance to the AMPs but resistance increased to ciprofloxacin by 128 times after 30 passages. Only peptides reduced biofilms of ciprofloxacin resistant cells. The antibiofilm effect of melimine with ciprofloxacin was more (27%) than with melimine alone at 1X MIC (p < 0.001). Similarly, at 1X MIC the combination of Mel4 and ciprofloxacin produced more (48%) biofilm disruption than Mel4 alone (p < 0.001). Combinations of either of the peptides with ciprofloxacin at 2X MIC released 66 nM ATP, more than either peptide alone (p 0.005). At 2X MIC, only melimine in combination with ciprofloxacin released DNA/RNA which was 3 times more than released by melimine alone (p = 0.043). These results suggest the potential use of melimine and Mel4 with conventional antibiotics for the treatments of S. aureus biofilms.
Subject: Life Sciences, Microbiology Keywords: Polyhydroxyalkanoates; mcl-PHA; scl-PHA; Post-transcriptional regulation; Riboregulation; Small non-coding RNAs
Online: 23 August 2021 (10:43:23 CEST)
The large production of non-degradable petrol-based plastics has become a major global issue due to its environmental pollution. Biopolymers produced by microorganisms such as polyhydroxyalkanoates (PHAs) are gaining potential as a sustainable alternative, but the high cost associated to their industrial production has been a limiting factor. Post-transcriptional regulation is a key step to control gene expression in changing environments and has been reported to play a major role in numerous cellular processes. However, limited reports are available concerning the regulation of PHA accumulation in bacteria, and many essential regulatory factors still need to be identified. Here, we review studies where the synthesis of PHA has been reported to be regulated at the post-transcriptional level, and we analyze the RNA-mediated networks involved. Finally, we discuss the forthcoming research on riboregulation, synthetic and metabolic engineering which could lead to improved strategies for PHAs synthesis in industrial production, thereby reducing the costs currently associated with this procedure.
Thu, 19 August 2021
ARTICLE | doi:10.20944/preprints202108.0397.v1
Online: 19 August 2021 (10:30:53 CEST)
Background: The dairy industry heavily relies on fermentation processes driven in high proportion by Lactococcus lactis. The fermentation process can be perturbed or even stopped by bacteriophage activity leading to complete loss of fermentation batch or decreased quality product. Monitoring of the phage diversity and dynamics in the process allows to implement protective measures (e.g. starter rotation) in order to maintain unperturbed production.; Methods: Universal primers were used to amplify sequences of the 936, c2, and P335 Lactococcus phage types. The amplicons were sequences with Sanger method and obtained degenerate sequences were analyzed using simple bioinformatic pipeline in R environment.; Results: The most prevalent phage type is 936, followed by P335, whereas c2 type is less frequent.; Conclusions: Curd cheeses prepared on non-pasteurized milk based on native milk microbiota had higher diversity of phages distinct of these found in dairy plants. Sanger sequencing of heterogenous amplicons generated on metagenome DNA can be used to asses low-complexity microbiota diversity.
ARTICLE | doi:10.20944/preprints202105.0304.v2
Subject: Life Sciences, Microbiology Keywords: Enterococcus; QPS; GRAS; safety; milk; cheese; mountain area
Online: 19 August 2021 (06:31:01 CEST)
The latest EU regulation on geographical indications (EU Regulation No. 1151/2012) has intro-duced a set of new tools for the protection and enhancement of food products in rural areas, under the group name of optional quality term (OQT). The Commission Delegated EU Regulation, No. 665/2014, regulated the conditions for the use of the optional quality term «mountain product» (MP), to support the implementation of a mountain value chain. This new tool is aimed at pro-moting local development, maintaining the economic activities in mountain areas and redistrib-uting wealth, whilst, at the same time, promoting the territory. Pecorino and goat cheeses are typ-ical Italian cheeses made usually with whole raw ewe's or raw goat's milk, without starter cul-ture addition. In an attempt to characterize these productions, the aim of this study was to inves-tigate the evolution of enterococci during the production and ripening of Pecorino cheese made in three different farms, located in Umbria, Italy in areas facing natural or other specific constraints as stipulated by Regulation 1305/2013 on support for rural development by the European Agri-cultural Fund for Rural Development (EAFRD). Enterococci are enteric organisms which are commonly isolated from ewe and goat's milk production in Umbria, Italy. Counts of enterococci in raw milk ranged from 1.75 for ovine milk to 3.62 for ewe milk and a marked reduction was observed after thermization especially in ovine milk. Out of 100 isolates, 69 were E. faecium, 23 E. durans, 8 E. faecalis and 2 E. casseliflavus and the distribution of species between farms and be-tween samples showed a prevalence of E. faecium in ovine farms and E. durans in ewes farms, with an equal distribution between samples. High percentages of susceptible isolates were found for amoxicillin/clavulanic acid, ampicillin, chloramphenicol, sulphamethoxazole, sulphameth-oxazole/trimethoprim, ticarcillin, vancomycin. A high prevalence of resistant strains (> 30%) was observed for amikacin, ciprofloxacin, ceftriaxone, kanamycin, tetracycline. A comparison of this results with those of previous works on similar dairy products revealed high levels of resistance to antimicrobials which needs to be addressed.
Wed, 18 August 2021
ARTICLE | doi:10.20944/preprints202108.0370.v1
Subject: Life Sciences, Microbiology Keywords: wood-rotting basidiomycetes; carbon source; cellulases; regulation of synthesis; saccharification
Online: 18 August 2021 (07:41:08 CEST)
In the present study, the polysaccharide-hydrolyzing secretomes of Irpex lacteus BCC104, Pycnoporus coccineus BCC310, and Schizophyllum commune BCC632 were analyzed in submerged fermentation conditions to elucidate the effect of chemically and structurally different carbon sources on the expression of cellulases and xylanase. Among polymeric substrates, crystalline cellulose appeared to be the best carbon source providing the highest endoglucanase, total cellulase, and xylanase activities. Mandarin pomace as a growth substrate for S. commune allowed to achieve comparatively high volumetric activities of all target enzymes while wheat straw induced a significant secretion of cellulase and xylanase activities of I. lacteus and P. coccineus. A synergistic effect on the secretion of cellulases and xylanases by the tested fungi was observed when crystalline cellulose was combined with mandarin pomace. In I. lacteus the cellulase and xylanase production is inducible in the presence of cellulose-rich substrates but is suppressed in the presence of an excess of easily metabolizable carbon source. These enzymes are expressed in a coordinated manner under all conditions studied. It was shown that the substitution of glucose in the inoculum medium with Avicel provides accelerated enzyme production by I. lacteus and higher cellulase and xylanase activities of the fungus. These results add new knowledge to the physiology of basidiomycetes to improve cellulase production.
Tue, 17 August 2021
ARTICLE | doi:10.20944/preprints202108.0354.v1
Subject: Life Sciences, Microbiology Keywords: Alternaria tenuissima; extract; bioassays; PCA; tenuazonic acid; Galleria mellonella; Zophobas morio; Acheta domesticus; Tetranychus urticae; Schizaphis graminum; Sf9
Online: 17 August 2021 (08:36:56 CEST)
Study of fungal antibiotics in their competitive interactions with arthropods may lead to development novel biorational insecticides. Extracts of Alternaria tenuissima MFP253011 obtained by various methods showed a wide range of biological activity, including entomotoxic properties. Analysis of their composition and bioactivity allowed to reveal several known mycotoxins and unidentified compounds that may be involved in entomotoxic activity of the extracts. Among them, tenuazonic acid (TeA), which was the major component of the A. tenuissima extracts, was found the most likely to have larvicidal activity against Galleria mellonella. In the intrahaemocoel injection bioassay, TeA was toxic to G. mellonella and of Zophobas morio with LT50 6 and 2 days, respectively, at the level of 50 µg/larva. Administered orally, TeA inhibited growth of G. mellonella larvae and caused mortality of Acheta domesticus imagines (LT50 7 days) at a concentration of 250 µg/g of feed. TeA showed weak contact-intestinal activity against the two phytophages, Tetranychus urticae and Schizaphis graminum, causing the 12 and 40% of mortality at a concentration of 1 mg/mL. TeA was cytotoxic to Sf9 cell line (IC50 25 µg/mL). Thus, model insect G. mellonella and cell line Sf9 could be used for a further toxicological characterization of TeA.
REVIEW | doi:10.20944/preprints202108.0348.v1
Subject: Life Sciences, Microbiology Keywords: Enteric pathogenic Escherichia coli; E. coli pathotypes; Virulence factor genes
Online: 17 August 2021 (08:16:59 CEST)
Abstract: Escherichia coli are remarkably versatile microorganisms and important members of the normal intestinal microbiota of humans and animals. This harmless commensal organism can acquire a mixture of comprehensive mobile genetic elements that contain genes encoding viru-lence factors, becoming an emerging human pathogen capable of causing a broad spectrum of intestinal and extraintestinal diseases. Nine definite enteric E. coli pathotypes have been well characterized, causing diseases ranging from various gastrointestinal disorders to urinary tract infections. These pathotypes employ many virulence factors and effectors subverting the func-tions of host cells to mediate its virulence and pathogenesis. This review summarizes new de-velopments in our understanding of diverse virulence factors associated encoding genes used by different pathotypes of enteric pathogenic E. coli to cause intestinal and extraintestinal diseases in humans.
Mon, 16 August 2021
ARTICLE | doi:10.20944/preprints202108.0340.v1
Subject: Life Sciences, Microbiology Keywords: Escherichia coli; Antimicrobial resistance; Food samples; Phylogenetic group; Genetic diversity
Online: 16 August 2021 (13:35:58 CEST)
The emergence of multi-drug resistant E. coli is an important matter of increasing considerable concern to global public health. The aim of this study was to investigate the incidence, antibiotic resistance pattern, phylogroups and genetic variation of E. coli isolates from raw milk, vegetable salad and ground meat samples. Methods: Culture-based techniques, Kirby-Bauer disk diffusion susceptibility testing, PCR and RAPD assays were used to determine the incidence rate, antimicrobial resistance pattern, phylogenetic groups and genetic diversity of the E. coli isolates. Results: E. coli isolates were highly resistant to amoxicillin (79.16%), trime-thoprim-sulfamethoxazole (70.83%), amoxicillin-clavulanic acid (62.50%), tetracycline (54.16%), chloramphenicol (54.16%), nitrofurantoin (54.16%), ampicillin (45.83%), streptomycin (45.83%), and kanamycin (33.33%); and completely susceptible to norfloxacin and azithromycin. 70.83% of the isolates were multi-drug resistant. Most E. coli isolates (46%) belonged to phylogroup A. RAPD with UBC245 primer categorized the isolates into 11 clusters. A high level of genetic di-versity was found among the isolates; however, 33.3% of the isolates were grouped in a major cluster (R5). Conclusions: Antibiotic resistance patterns are randomly distributed among the ge-netic clusters. Novel, practical, efficient food safety control and surveillance systems of multi-drug resistant foodborne pathogens are required to control the foodborne pathogen contamina-tion.
ARTICLE | doi:10.20944/preprints202108.0313.v1
Subject: Life Sciences, Microbiology Keywords: Pecorino di Farindola cheese; lactic acid bacteria (LAB); molecular characterization; Lacticaseibacillus paracasei selected culture; cheese making trial
Online: 16 August 2021 (08:47:09 CEST)
This study focused on the characterization of lactic acid bacteria (LAB) in a renowned traditional Italian cheese, Pecorino di Farindola, to select an autochthonous culture and investigate its po-tential for the improvement of safety and functional properties. Two hundred and six LAB isolated throughout production and maturation from nine cheese lots of three farms were identified by 16S rRNA gene sequencing and tested for the presence of genes encoding virulence factors, vancomycin resistance (for enterococci), biogenic amines (BAs) and bacteriocin production, for antimicrobial activity, and for the capacity to survive in the gastro-intestinal tract (GIT) based on tolerance to low pH and bile salts and adhesion to CaCo-2 cells. A Lacticaseibacillus paracasei isolate was used in cheese making and determined a decline of spiked Listeria monocytogenes and Escherichia coli O157 faster than in control cheese. The autochthonous bacterial groups were numerically unaffected, apart from lactobacilli that were recovered in higher numbers in the cheese with added L. paracasei. Based on Repetitive Extragenic Palyndrome (Rep) PCR profiles, the added strain possibly dominated until day 88 in cheese. Results encourage further trials with autochthonous cultures to efficiently inhibit hazardous bacteria and enrich a functional microbiota in Pecorino di Farindola and similar cheeses.
ARTICLE | doi:10.20944/preprints202108.0312.v1
Subject: Life Sciences, Microbiology Keywords: Komagataeibacter rhaeticus; Bacterial cellulose; Crude glycerol; Minimal medium; Whole-genome analysis; Acetate
Online: 16 August 2021 (08:32:19 CEST)
Komagataeibacter spp. have been used for the bioconversion of industrial wastes and lignocellulosic hydrolysates to bacterial cellulose (BC). Recently studies have demonstrated the capacity of Komagataeibacter spp. in the biotransformation of inhibitors found in lignocellulosic hydrolysates, aromatic lignin-derived monomers (LDMs) and acetate. In general, detoxification and BC synthesis from lignocellulosic inhibitors requires a carbon flow from acetyl-coA towards tricarboxylic acid and gluconeogenesis, respectively. However, the related molecular aspects have not yet been identified in Komagataeibacter spp. In this study, we isolated a cellulose producing bacteria capable of synthesizing BC in a minimal medium containing crude glycerol, a by-product from biodiesel production process. The isolate, affiliated to Komagataeibacter genus, synthesized cellulose in minimal medium containing glucose (3.3±0.3 g/L), pure glycerol (2.2±0.1 g/L) and crude glycerol (2.1±0.1 g/L). Genome assembly and annotation identified four copies of bacterial cellulose synthase operon and genes for redirecting the carbon from central metabolic pathway to gluconeogenesis. According to the genome annotations, a BC production route from acetyl-CoA, a central metabolic intermediate, was hypothesized and was validated using acetate. We identified that when K. rhaeticus ENS9b was grown in minimal medium supplemented with acetate, BC production was not observed. However, in presence of readily utilizable substrate, such as spent yeast hydrolysate, acetate supplementation improved BC synthesis.
Sat, 14 August 2021
ARTICLE | doi:10.20944/preprints202108.0306.v1
Subject: Life Sciences, Microbiology Keywords: aminoglycoside resistance; structure-activity relationship; aminoglycoside modifying enzymes, acetyltransferase, Acinetobacter
Online: 14 August 2021 (14:12:06 CEST)
The aminoglycoside 6′-N-acetyltransferase type Ib [AAC(6′)-Ib] is a common cause of resistance to amikacin and other aminoglycosides in Gram-negatives. Utilization of mixture-based combinatorial libraries and application of the positional scanning strategy identified an inhibitor of AAC(6′)-Ib. This inhibitor’s chemical structure consists of a pyrrolidine pentamine scaffold substituted at four locations (R1, R3, R4, and R5). The substituents are two S-phenyl (R1 and R4), an S-hydroxymethyl (R3), and a 3-phenylbutyl (R5) groups. Another location, R2, does not have a substitution, but it is named because its stereochemistry was modified in some compounds utilized in this study. Structure-activity relationship (SAR) analysis using derivatives with different functionalities, modified stereochemistry, and truncations were carried out by assessing the effect of the addition of each compound at 8 µM to 16 µg/ml amikacin-containing media and performing checkerboard assays varying the concentrations of the inhibitor analogs and the antibiotic. The results showed that: 1) the aromatic functionalities at R1 and R4 are essential, but the stereochemistry is essential only at R4, 2) the stereochemical conformation at R2 is critical, 3) the hydroxyl moiety at R3 as well as stereoconformation are required for full inhibitory activity, 4) the phenyl functionality at R5 is not essential and can be replaced by aliphatic groups, 5) the location of the phenyl group on the butyl carbon chain at R5 is not essential, 6) the length of the aliphatic chain at R5 is not critical, 7) all truncations of the scaffold resulted in inactive compounds. Molecular docking revealed that all compounds preferentially bind to the kanamycin C binding cavity, and binding affinity correlates with the experimental data for most of the compounds evaluated. The SAR results in this study will serve as the basis for the design of new analogs in an effort to improve their ability to induce phenotypic conversion to susceptibility in amikacin-resistant pathogens.
Thu, 12 August 2021
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.
Wed, 11 August 2021
ARTICLE | doi:10.20944/preprints202108.0263.v1
Subject: Life Sciences, Microbiology Keywords: antimicrobial; antimicrobial use; antimicrobial resistance; antibiotic utilization; Tanzania; defined daily dose, Anatomical Therapeutic and Chemical Classification
Online: 11 August 2021 (14:42:57 CEST)
Antimicrobial use (AMU) is one of the major drivers of emerging antimicrobial resistance (AMR). Surveillance of AMU, a pillar of AMR stewardship (AMS), helps devise strategies to mitigate AMR. This descriptive, longitudinal retrospective study quantified the trends in human antibiotic utilization between 2010 and 2016 using data on all antibiotics imported for systemic human use into Tanzania's mainland. Regression and time series analyses were used to establish trends in antibiotics use. A total of 12,073 records for antibiotics were retrieved, totaling 154.51Daily Defined Doses per 1,000 inhabitants per day (DID) with a mean (± standard deviation) of 22.07 (±48.85) DID. The private sector contributed 93.76%% of utilized antibiotics. The top-ranking antibiotics were amoxicillin, metronidazole, tetracycline, ciprofloxacin and cefalexin. The DDIs and percentage contribution of these antibiotics were 53.78 (34.81%), 23.86 (15.44), 20.53 (13.29), 9.27 (6.0) and 6.94 (4.49), respectively. The time series model predicted significant increase in utilization(p-value =0.002). The model forecasted that by 2022, the total antibiotics consumed would reach 89.6 DIDs, corresponding to a 13-fold increase compared to 2010. Government intervention to curb inappropriate antibiotic utilization to mitigate the rising threat of antibiotic resistance should focus on implementing AMS programs in pharmacies and hospitals in Tanzania.
Mon, 9 August 2021
ARTICLE | doi:10.20944/preprints202108.0199.v1
Online: 9 August 2021 (14:59:38 CEST)
Non-tuberculous mycobacteria (NTM) are opportunistic pathogens that cause illness primarily in the elderly, in the immunocompromised or in patients with underlying lung disease. Mycobacterium chimaera is a NTM species belonging to the M. avium Complex (MAC) group of species. Since 2013, a global outbreak of M. chimaera infection related to heater-cooler units (HCU) used in cardio-thoracic surgery has been identified. This outbreak was caused by a single strain of M. chimaera. In order to estimate the prevalence of this outbreak strain in Israel, we sampled M. chimaera from several HCU machines in Israel, as well as from patients, sequenced their genomes and compared them to the outbreak strain. The presence of mixed mycobacteria species in the samples complicated the analysis of obtained sequences. By applying a metagenomic binning strategy, we were able to obtain genomes of single strains from the mixed samples, and characterized them. M. chimaera strains were compared to each other and to previously reported genomes from other countries. The strain causing the outbreak related to the HCU machines was identified in several such machines in Israel but not in any of the clinical samples.
Tue, 20 July 2021
ARTICLE | doi:10.20944/preprints202107.0457.v1
Subject: Life Sciences, Microbiology Keywords: Latilactobacillus sakei; comparative genomics; carbohydrate utilization; antibiotic tolerance; CRISPR-Cas
Online: 20 July 2021 (15:02:42 CEST)
Increasing attention has been paid to the potential probiotic effects of Latilactobacillus sakei. To explore the genetic diversity of L. sakei, 14 strains isolated from different niches (feces, fermented kimchi and meat products) and 54 published strains were compared and analyzed. The results showed that the average genome size and GC content of L. sakei were 1.98Mb and 41.22%, respectively. Its core genome mainly encodes translation and transcription, amino acid synthesis, glucose metabolism and defense functions. L. sakei has an open pan-genomic characteristics, and its pan-gene curve shows an upward trend. L. sakei has open pan-genome feature, and its pan-genome curve is on the rise. The genetic diversity of L. sakei is mainly reflected in carbohydrate utilization, antibiotic tolerance, and immune/competition-related factors, such as clustering regular interval short palindromic repeat sequence (CRISPR)-Cas. The CRISPR system is mainly IIA type, and a few are IIC types. This work provides a basis for the study of this species.
Mon, 7 June 2021
ARTICLE | doi:10.20944/preprints202106.0170.v1
Subject: Life Sciences, Microbiology Keywords: dromedary camels, ticks, heartwater, zoonosis, tick-borne pathogens, Anaplasma, Coxiella, Ehrlichia, Rickettsia
Online: 7 June 2021 (12:39:26 CEST)
Ticks and tick-borne pathogens (TBPs) are major constraints to camel health and production, yet epidemiological data on their diversity and impact on dromedary camels are limited. We sur-veyed the diversity of ticks and TBPs associated with camels and co-grazing sheep at 12 sites in Marsabit County, northern Kenya. We screened blood and ticks (858 pools) collected from 296 camels and 77 sheep for bacterial and protozoan TBPs by high-resolution melting analysis and sequencing of PCR products. Hyalomma (75.7%), Amblyomma (17.6%) and Rhipicephalus (6.7%) spp. ticks were morphologically identified and confirmed by molecular analyses. We detected TBP DNA in 80.1% of blood samples from 296 healthy camels. “Candidatus Anaplasma camelii”, “Candidatus Ehrlichia regneryi” and Coxiella burnetii were detected in both camels and associ-ated ticks, and Ehrlichia chaffeensis, Rickettsia africae, Rickettsia aeschlimannii and Coxiella endo-symbionts were detected in camel ticks. We also detected Ehrlichia ruminantium, responsible for heartwater disease in ruminants, in Amblyomma ticks infesting camels and sheep and in sheep blood, indicating its endemicity in Marsabit. Our findings also suggest that camels and/or the ticks infesting them are reservoirs of zoonotic Q fever (C. burnetii), ehrlichiosis (E. chaffeensis), and rickettsiosis (R. africae), which pose a public health threat to pastoralist communities.
Tue, 11 May 2021
Subject: Life Sciences, Microbiology Keywords: Chryseobacterium indologenes; Oral abscess; Ball Python
Online: 11 May 2021 (14:53:22 CEST)
Abstract: Chryseobacterium indologenes is an opportunistic pathogen isolated from human infec-tions and rarely from some aquatic animals. A 3-year-old male ball python (Python regius) was admitted to the veterinary clinic by a pet owner because of acute respiratory and swallowing failure. During physical examinations, oral secretions and abscesses were observed on the mouth cavity and throat of the animal. After microbiological analysis including isolation, identi-fication, and 16s rRNA sequencing; Ch. indologenes was detected as the main cause of the oral abscess in this case. Phylogenetic relatedness analysis showed a close relationship between this isolate and other strains isolated from human infections. Antimicrobial susceptibility testing re-vealed that the isolate was multi-drug resistant. However, it was very sensitive to minocycline, ceftazidime, and tetracycline. The patient was treated by antibiotic therapy and completely re-covered after two weeks. To our best knowledge, this is the first incidence of Ch. indologenes in an oral abscess in a ball python. As result we would consider this organism as an opportunistic animal pathogen with zoonotic potentiality.
Tue, 2 March 2021
ARTICLE | doi:10.20944/preprints202103.0109.v1
Subject: Life Sciences, Microbiology Keywords: Pythiosis; Pythium insidiosum; Environment isolate; DNA barcode; Biotyping
Online: 2 March 2021 (16:41:34 CET)
Pythium insidiosum causes pythiosis, a fatal infectious disease of humans and animals worldwide. Prompt diagnosis and treatment are essential to improve the clinical outcome of pythiosis. Diagnosis of P. insidiosum relies on immunological, molecular, and proteomic assays. The main treatment of pythiosis aims to surgically remove all affected tissue to prevent recurrent infection. Due to the marked increase in case reports, pythiosis has become a public health concern. Thailand is an endemic area of human pythiosis. To obtain a complete picture of how the pathogen circulates in the environment, we surveyed the presence of P. insidiosum in urban (Bangkok) and rural areas of Thailand. We employed the hair-baiting technique to screen for P. insidiosum in 500 water samples. Twenty-seven culture-positive samples were identified as P. insidiosum by multiplex PCR, multi-DNA barcode (rDNA, cox1, cox2), and mass spectrometric analyses. These environmental strains of P. insidiosum fell into clade-I and -II genotypes and exhibited a close phylogenetic/proteomic relationship with Thai clinical strains. Biodiversity of the environmental strains also existed in a local habitat. In conclusion, P. insidiosum is widespread in Thailand. A better understanding of the ecological niche of P. insidiosum could lead to the effective prevention and control of this pathogen.
Mon, 25 January 2021
BRIEF REPORT | doi:10.20944/preprints202101.0495.v1
Subject: Life Sciences, Microbiology Keywords: Sulforaphane; Alcohol; Burkholderia; Binge drinking; MHS cells; Melioidosis
Online: 25 January 2021 (13:03:02 CET)
Binge drinking is associated with increased mortality and morbidity. Burkholderia pseudomallei, the causative agent of pneumonic melioidosis can occur in healthy humans; however, binge alcohol intoxication is a major risk factor. Previous findings indicate that a single binge alcohol episode increases Burkholderia spp. infection by reducing alveolar macrophage function. The aim of this study was to test the ability of the phytonutrient sulforaphane (SFN) to rescue the phagocytic function of alveolar macrophages when infected with Burkholderia spp. in vitro. B. thailandensis E264 was used as a useful BSL-1 model to determine the effects of SFN pre-treatment. The primary outcome was macrophage phagocytic killing, while the secondary outcome was the nuclear factor (erythroid-derived 2)-like (Nrf2) signaling response measured by western blot analysis. Results indicate that alveolar macrophages pre-treated with SFN (5 M) and challenged with 0.2% (v/v) alcohol for 3 or 8 h prior to live B. thailandensis infection improved intracellular killing of B. thailandensis ~2-fold compared to MH-S cells treated with alcohol alone. These data demonstrate that SFN may be an effective pre-treatment option to prevent alcohol mediated immune dysfunction and restore macrophage phagocytic killing of Burkholderia spp. and other similar opportunistic pathogens.
Mon, 21 December 2020
ARTICLE | doi:10.20944/preprints202012.0511.v1
Subject: Life Sciences, Microbiology Keywords: Antioxidant enzymes; hemibiotroph; reactive oxygen species; host-pathogen interaction; sporulation
Online: 21 December 2020 (11:23:57 CET)
Wheat blast caused by the hemibiotroph fungal pathogen Magnaporthe oryzae Triticum (MoT) pathotype, is a destructive disease of wheat in South America and Bangladesh. Generation of reactive oxygen species (ROS) is one of the defense responses in plants during the infection process by a pathogen. However, empirical evidence on regulation of ROS in wheat and other host and non-host plants towards MoT is limited. This study aimed to determine the susceptibility of some major cereals and weeds of Bangladesh and compare the antioxidant enzyme activities in host and non-host plants in response to artificial inoculation by MoT. Seedlings of wheat, maize, barley and swamp rice grass were susceptible to MoT and produced considerable number of conidia on infected leaves (host). Rice seedlings showed a resistant response in our laboratory conditions (non-host). The activities of ROS-detoxifying enzymes; catalase (CAT), ascorbate peroxidase (APX), Glutathione peroxidase (GPX), Glutathione S-transferase (GST), Peroxidase (POX) increased in all plants after inoculation by MoT with a few exceptions. Interestingly, an early and very high accumulation of CAT was observed within 24 hours of inoculation (hai) in wheat, barley, maize and swamp rice grass while H2O2 concentration was low during that time and immediately after that (24-48 hai). In contrast, an early and high accumulation of H2O2 was observed in rice at 48 hai with little CAT activity only at a late stage. The APX, GST and POD activity was also increased due to the inoculation of MoT at the early stage of infection in rice but were very high at the disease progression stage in wheat, barley, maize and swamp rice grass. GPX activity gradually decreased with the increase of time in rice. Taken together, our results suggest that a robust and late induction of most of the antioxidant enzyme activities occurs in susceptible/host plants whereas an early induction of antioxidant enzyme activities occurs in resistant/ non-host plant but with slow kinetics.
Tue, 10 November 2020
REVIEW | doi:10.20944/preprints202011.0062.v2
Subject: Life Sciences, Microbiology Keywords: Type VI Secretion System; antieukaryotic effectors; interkingdom competition; virulence
Online: 10 November 2020 (16:10:18 CET)
The type 6 protein secretion system (T6SS) is prevalently utilized by Gram-negative bacteria to compete for resources and space. Upon activation, toxic effectors from this secretion system are translocated into the competitor prokaryote or eukaryote in a contact-dependent manner. While much has been reported on T6SS-mediated prokaryotic competition, very little is understood about the mechanisms of bacterial interactions with eukaryotic hosts. Likewise, many virulent T6SS effectors are known to be antibacterial. In recent years, however, evidence has emerged on numerous T6SS effectors that interact with related immunity proteins in a range of eukaryotic hosts. Insights into how this effector-immunity pairing alters the physiological responses of the recipient organism might provide opportunities relating to the T6SS agricultural and biotherapeutic applications. We, therefore, summarize the impacts of the T6SS effectors with a special focus on bacterial interactions with animals, plants, and fungi. We further briefly discuss pipelines that are currently used to characterize antieukaryotic T6SS effectors.
Mon, 2 November 2020
ARTICLE | doi:10.20944/preprints202011.0024.v1
Subject: Life Sciences, Microbiology Keywords: Bacteriophage, tailed phages; icosahedral capsids; capsid modeling; statistical learning; isolated genomes; metagenome-assembled genomes.
Online: 2 November 2020 (11:05:49 CET)
Tailed phages are the most abundant and diverse group of viruses on the planet. Yet, the smallest tailed phages display relatively complex capsids and large genomes compared to other viruses. The lack of tailed phages forming the common icosahedral capsid architectures T = 1 and T = 3 is puzzling. Here, we extracted geometrical features from high-resolution tailed phage capsid reconstructions and built a statistical model based on physical principles to predict the capsid diameter and genome length of the missing small tailed phage capsids. We applied the model to 3,348 isolated tailed phage genomes and 1,496 gut metagenome-assembled tailed phage genomes. Four isolated tailed phages were predicted to form T = 3 icosahedral capsids, and twenty-one metagenome-assembled tailed phages were predicted to form T < 3 capsids. The smallest capsid predicted was a T = 4/3 ≈ 1.33 architecture. No tailed phages were predicted to form the smallest icosahedral architecture, T = 1. We discuss the feasibility of the missing T = 1 tailed phage capsids and the implications of isolating and characterizing small tailed phages for viral evolution and phage therapy.
Thu, 24 September 2020
ARTICLE | doi:10.20944/preprints202009.0584.v1
Subject: Life Sciences, Microbiology Keywords: fungal community; gut mycobiota; diversity; ITS metabarcoding; intestinal parasites; children; Mali
Online: 24 September 2020 (12:24:53 CEST)
Eukaryotic enteric pathogens (EEP) are a public health issue in tropical areas. Yet, their interactions with the gut mycobiota remain poorly understood. We conducted a cross-sectional study in Malian children to analyze the impact of EEP on the gut fungal community. EEP were assessed by qPCR and the gut mycobiota was characterized by ITS1-2 metabarcoding in stool samples collected from 296 children. The 100 controls, in whom no EEP was detected, were compared to: a) 196 children with ≥1 EEP; b) 91 with only Blastocystis; c) 35 with only Giardia intestinalis; and d) 12 with another (<1% each) EPP. The gut fungal community structure was homogenous in each children’s group. Linear size-effect discriminant analysis highlighted five relatively more abundant species, including Fusarium longipes and Penicillium caseifulvum, in children with ≥1 EEP, whereas 28, including Aspergillus sydowii and Microdochium colombiense were more abundant in controls. Fusarium, Pyxidiophora, and Stereum abundance was higher in Blastocystis-infected children, whereas Ogataea and Allocryptovalsa were more abundant in controls. Sordariales and Mortierellales abundance was higher in Giardia intestinalis-infected children, whereas Agaricales and Capnodiales abundance was higher in controls. In conclusion, EEP do not significantly alter the gut fungal community structure, and further studies are warranted to confirm our findings that particular taxa are associated with susceptibility or resistance to specific EEP.
Tue, 22 September 2020
Subject: Life Sciences, Microbiology Keywords: Quorum sensing; Quorum quenching; AHL molecules; 16S rRNA
Online: 22 September 2020 (09:43:55 CEST)
N-Acyl-homoserine lactones, the Quorum sensing signaling molecules predominantly found in gram-negative bacteria, which regulate several bacterial genes including virulence and antibiotic resistant genes. The study was aimed to identify and characterize QS and QQ bacteria from different samples. 5 samples with different ecological background were collected from soil and 10 samples from hospital setup. 31 different bacteria were isolated with either QS or QQ activities all together. CV026 and A136 biosensor strains were used for the detection of QS and QQ positive strains. QS activity was observed by cross streaking test of bacteria against CV026, it was affirmed that 13 isolates from the soil and 5 from hospital equipment’s showed positive QS activity. QQ activity of each isolate was tested by well diffusion assay, C6-HSL and C12-HSL were our candidate AHL molecules. The AHL molecule degradation was detected in 4 isolates of soil and none from the samples obtained from hospital setup. The total of 6 strongly positive QS and QQ isolates were identified and selected for 16S rRNA gene sequencing. The phylogenetic analysis revealed that these isolates were closely related to Pseudomonas, Bacillus and Exiguobacterium genera. In contrast, 1 Gram positive bacterial isolate was also purified with QS potential.
Mon, 21 September 2020
ARTICLE | doi:10.20944/preprints202009.0494.v1
Online: 21 September 2020 (04:26:52 CEST)
Extended-spectrum β-lactamase (ESBL)-producing Escherichia coli is a serious-global public health issue. A total of 292 E. coli isolates obtained from fecal samples of pigs in Central (n = 103) and Northeastern (n = 189) provinces of Thailand were included in this study. Eighty-six E. coli isolates were phenotypically confirmed to be β-lactamase producers (29.5%) and screened for the presence of β-lactamase genes. The genes in CTX-M family was most frequently found (90.7%). The blaCTX-M-15 gene (59.3%) was predominantly identified CTX-M genotype, followed by blaCTX-M-14 (31.4%) and blaCTX-M-4 (25.6%). The blaTEM-1 gene was prevalent (75.6%). The blaCTX-M-4 and blaCTX-M-14 genes were located on conjugative plasmid. The results highlight healthy pigs as reservoirs of ESBL-producing E. coli carrying ESBL genes that could be horizontally transferred.
Sun, 20 September 2020
ARTICLE | doi:10.20944/preprints202009.0485.v1
Subject: Life Sciences, Microbiology Keywords: Characterisation; Epidemiology; ESBL; Escherichia coli
Online: 20 September 2020 (15:46:21 CEST)
.The emergence and spread of antimicrobial resistance genes and resistant bacteria does not recognized animal, human or geographic borders. Addressing this threat requires a combination of multidisciplinary approach involving human, animal and environmental health (One Health). Because antimicrobial agents used in veterinary medicine maybe the same or like those in human medicine. Extended-spectrum beta lactamase (ESBL) E. coli is a growing public health problem worldwide, and the Agri-Food industry is constantly becoming sources of clinically important ESBL bacteria. Accordingly, the aim of this study was to investigate the occurrence and characteristics of ESBL-producing E. coli from dairy cattle, milk, and the farm environment. E. coli isolates were identified by their 16sRNA and their ESBL production was confirmed by ESBL-CHROMagar media and double disk diffusion method. Genotypes of ESBL producers were characterised using mPCR assay. Among the examined samples, 18(4.8 %) were positive for ESBL-producing E. coli. Of these, 66.7% were from milk, 27.8% and 5.5% were from farm environment and faecal samples respectively. Predominant ESBL Genotype identified were a combination of both TEM and CTX-M in eight out of 18 (44.4%) isolates. Four (22.2%) isolates produced CTX-M gene, two (11.1%) isolates produced TEM gene and four (22.2%) remaining isolates produced ESBL genes other than TEM, SHV, CTX-M and OXA. The SHV and OXA gene were not detected in all 18 isolates. The occurrence of these genotype in indicator organisms from dairy cattle, milk, and farm environment further re-enforced the potentials of food-animals as sources of infection for humans via the food chain. Thus, consolidating the need for the adoption of tripartite One Health approach in surveillance and monitoring antimicrobial resistance
REVIEW | doi:10.20944/preprints202009.0471.v1
Subject: Life Sciences, Microbiology Keywords: Burkholderia pseudomallei; Mycobacterium tuberculosis; Multi nucleated giant cell; persistence; chronic infection
Online: 20 September 2020 (14:31:03 CEST)
This review provides a snapshot of chronic bacterial infections through the lens of Burkholderia pseudomallei; detailing its ability to establish multi-nucleated giant cells (MNGC) within the host, leading to the formation of pyogranulomatous lesions. We explore the role of MNGC in melioidosis disease progression and pathology by comparing the similarities and differences of melioidosis to tuberculosis, outlining the concerted events in pathogenesis that lead to MNGC formation, discussing the factors that influence MNGC formation and how they fit into clinical findings reported in chronic cases. Finally, we speculate about future models and techniques that can be used to delineate the mechanisms of MNGC formation and function.
Thu, 17 September 2020
REVIEW | doi:10.20944/preprints202009.0405.v1
Subject: Life Sciences, Microbiology Keywords: horizontal gene transfer; bacterial conjugation; phenotypic conversion; drug-resistance dissemination; bacterial biofilms; mobile plasmids; F plasmid
Online: 17 September 2020 (12:00:29 CEST)
Bacterial conjugation, also referred to as bacterial sex, is a major horizontal gene transfer mechanism where the DNA is transferred from a donor to a recipient bacterium by direct contact. Conjugation is universally conserved among bacteria and occurs in a wide range of environments (soil, plant surfaces, water, sewage, biofilms and host-associated bacterial communities). Within these habitats, conjugation drives the rapid evolution and adaptation of bacterial strains by mediating the propagation of various metabolic properties, including symbiotic life-style, virulence, biofilm formation, or resistance to heavy metals and, most importantly, resistance to antibiotics. These properties make of conjugation a fundamentally important process at the center of extensive study. Here, we review the key steps of conjugation by following the life-cycle of the F plasmid during transfer from the donor to the recipient cell. We also discuss our current knowledge of the extent and impact of conjugation within an environmentally and clinically relevant bacterial habitat, bacterial biofilms.
Sat, 12 September 2020
ARTICLE | doi:10.20944/preprints202009.0273.v1
Subject: Life Sciences, Microbiology Keywords: Chromobacterium vaccinii; biofilm; sharing goods; social cheater; bog microbiome; bacterial genome, violacein, cold adaptation, IDBac, QS mutant
Online: 12 September 2020 (12:04:38 CEST)
Chromobacterium species are common in tropical and subtropical zones in environmental water samples and believed to «tropical» species. Here we describe an environmental case of resident Chromobacterium vaccinii in biofilms associated with Carex spp. roots in Moscow region, Russia (warm-summer humid continental climate zone). We performed broad characterization of individual properties as well as surrounding context for better understanding the premise of C. vaccinii survival during winter season. Genome properties of isolated strains propose some insights into adaptation to habit and biofilm mode of life, including social cheaters carrying ΔluxR mutation. Isolated C. vaccinii differs with previously described strains in some biochemical properties and some basic characteristics like fatty acid composition as well as unique genome features. Despite potential to modulate membrane fluidity and presence of several genes responsible for cold shock response, isolated C. vaccinii didn`t survive during exposure to 4 °C, while in initial complex biofilm it was able to survive for months in vitro at 4 °C. Surrounding bacterial community within the same biofilm with C. vaccinii represented a series of psychrophilic bacterial species which may share resistance to low temperatures with other species within biofilm and provide C. vaccinii opportunity to survive during cold winter season.
ARTICLE | doi:10.20944/preprints202009.0269.v1
Subject: Life Sciences, Microbiology Keywords: escherichia coli; dogs; virulence genes; antibiotic resistance; WGS; ST372; clonal structure
Online: 12 September 2020 (09:56:27 CEST)
Under one-health perspective and the worldwide antimicrobial resistance concern, we investigate extraintestinal pathogenic Escherichia coli (ExPEC), uropathogenic E. coli (UPEC), and multidrug resistant (MDR) E. coli from 197 isolates recovered from healthy dogs in Spain between 2013 and 2017. Ninety-one (46.2%) isolates were classified as ExPEC and/or UPEC including 50 clones, among which (i) four clones were dominant (B2-CH14-180-ST127, B2-CH52-14-ST141, B2-CH103-9-ST372 and F-CH4-58-ST64815) and (ii) 15 had been shown to be displayed by previously published isolates causing extraintestinal infections in humans. Twenty-eight (14.2%) isolates were classified as MDR, associated with B1, D and E phylogroups and included 24 clones, of which eight had also been identified among human isolates causing infections. We selected 23 ST372 strains, 21 healthy dogs faecal isolates and two human clinical isolates for whole genome sequencing and built a SNP-tree with these 23 genomes and 174 genomes (128 from canine strains and 46 from human strains) obtained from public databases. The analysis of these 197 genomes allowed to identify six clusters. Cluster 1 comprised 74.6% of the strain genomes that were mostly composed of canine strain genomes (P < 0.00001). Clusters 4 and 6 also included canine strain genomes, while clusters 2, 3 and 5 were significantly associated with human strain genomes. All these findings suggest that dogs are reservoirs of ExPEC, UPEC and MDR E. coli isolates with zoonotic potential.
ARTICLE | doi:10.20944/preprints202009.0266.v1
Subject: Life Sciences, Microbiology Keywords: hypogenous ectomycorrhizal fungi; truffles; soil nutrient; fungal community
Online: 12 September 2020 (08:04:07 CEST)
Truffles contribute to crucial dynamics in the soil systems, being involved in plentiful ecological functions important for ecosystems. Despite this, the interactions between truffles and surrounding mycobiota remain unknown. Here, we aimed to shed light on how much truffle species could affect its surrounding soil mycobiota. Using traditional chemical analysis and Illumina ITS amplicon sequencing, we compared soil nutrients and mycobiota surrounding two truffle species: Tuber indicum (Ti) and T. pseudohimalayense (Tp) inhabit in the same Pinus armandii forest in southwestern China. Tp soil was more acidic and had higher nutrients (total C, N, P contents) than Ti soil. Fungal richness and diversity of truffle ascomata and surrounding soils were significantly higher in Tp than in Ti. Redundancy analysis showed relationships between soil fungal taxa and soil properties had changed from negative (Tp) to positive (Ti) and shifted from a moisture-driving (Tp) to a total N-driving (Ti). Overall, our results showed that the interactions between truffle and soil system had been altered with species variation, although the causative peculiarity of these associations needs to be further studied.
Tue, 8 September 2020
COMMUNICATION | doi:10.20944/preprints202009.0186.v1
Online: 8 September 2020 (11:04:34 CEST)
Vibrio is a bacterial genus widely distributed in natural aquatic systems. Some Vibrio species are pathogenic and can cause severe diseases in both marine organisms and humans. Previous studies revealed a link between the current climate change and increased incidence of the Vibrio-associated diseases recently causing sanitary, economic and/or ecological problems worldwide. The conventional culture-based methods (e.g. cultivation of TCBS agar) used to monitor the presence of Vibrio spp. in environmental samples are not always straightforward and can underestimate the number of cells, especially if the microbial population contains a fraction of ‘dormant’ cells (e.g. cells in Viable but not Culturable (VBNC) state). However, this problem can be overcome by using alternative culture-free approaches such as Catalyzed Reporter Deposition-Fluorescence In situ Hybridization (CARD-FISH). To optimize CARD-FISH for efficient and reliable detection of Vibrio spp. in environmental samples, we have used both computer-assisted and experimental approaches. Our results demonstrate that the use of the optimized protocol along with a very specific probe, ViB572a, can offer the high sensitivity and selectivity of CARD-FISH detection of marine vibrios in natural seawater.
Mon, 7 September 2020
Subject: Life Sciences, Microbiology Keywords: Computational methods; machine learning; microbiome-host interactions
Online: 7 September 2020 (14:50:42 CEST)
The microbiome, by virtue of its interactions with the host, is implicated in various host functions including its influence on inflammation, nutrition, and homeostasis. Although driven by a complex combination of intrinsic and extrinsic factors, many chronic diseases such as diabetes, cancer, Inflammatory Bowel Disease among others are characterized by a disruption of microbial communities in at least one biological niche/organ system. Various molecular mechanisms between microbial and host components such as proteins, RNAs, metabolites etc have recently been elucidated, thus filling many gaps in our understanding of how the microbiome modulates host processes. Concurrently, high throughput technologies have enabled the profiling of heterogeneous datasets capturing community level changes in the microbiome as well as the host responses. However, due to pragmatic limitations with respect to parallel sampling and analytical procedures, big gaps still exist in terms of how the microbiome mechanistically influences host functions at a systems and community level. In the past decade, various computational biology and machine learning methodologies and approaches have been developed with an aim to fill these existing gaps. Due to the agnostic nature of the tools, they have been applied in various disease contexts to analyze and infer the interactions between the microbiome and host molecular components, and in the case of a few selected tools, on downstream host processes. Generally, most of the tools are enabled by frameworks to statistically or mechanistically integrate different types of -omic and meta -omic datasets followed by functional/biological interpretation. In this review, we provide an overview of the landscape of computational approaches for investigating mechanistic microbiome-host interactions and their potential benefit for basic and clinical research. These could include but are not limited to the development of activity and mechanism based biomarkers, uncovering mechanisms for therapeutic interventions and generating integrated signatures to stratify patients.
Sat, 5 September 2020
COMMUNICATION | doi:10.20944/preprints202009.0115.v1
Subject: Life Sciences, Microbiology Keywords: intramammary infection; spa typing; antimicrobial susceptibility; dairy cow
Online: 5 September 2020 (04:51:45 CEST)
In the present study, we aimed to determine the antimicrobial resistance and genetic structure of a population of S. aureus recovered from transient and persistent intramammary infections and nares/muzzles. We investigated the antimicrobial resistance of 189 S. aureus strains using a broad antimicrobial susceptibility profile. Furthermore, 107 S. aureus isolates were strain-typed using staphylococcal protein-A (spa) typing. Here, a great proportion of strains exhibited multidrug resistance to antimicrobials, including resistance to critically important antimicrobials, although no methicillin-resistant S. aureus strains were found. Our study did not strengthen the idea that extramammary niches (i.e., nares/muzzles) are an important source for S. aureus. A discrepancy in the antimicrobial resistance between S. aureus strains isolated from nasal/muzzles and milk samples was observed. Furthermore, S. aureus isolates from transient and persistent IMIs did not differ by spa typing, suggesting that the persistence of bovine IMIs was determined by cow factors. Thus, the high level of multidrug-resistant S. aureus found in the two herds studied together with the predominance of a well udder-adapted S. aureus strain may contribute to the history of the high prevalence of mastitis caused by S. aureus, leading to great animal and public health concerns.
Fri, 4 September 2020
ARTICLE | doi:10.20944/preprints202009.0106.v1
Subject: Life Sciences, Microbiology Keywords: Fish pathogen; host-pathogen interaction; proteomics; infection assays; virulence factors
Online: 4 September 2020 (12:51:22 CEST)
Piscirickettsia salmonis is an intracellular bacterial fish pathogen that causes piscirickettsiosis, a disease with numerous negative impacts in the Chilean salmon farming industry. Although transcriptomic studies of P. salmonis and its host have been performed, dual host-pathogen proteomic approaches during infection are still missing. Considering that gene expression not always corresponds with observed phenotype, and bacteriological culture studies inadequately reflect infection conditions, to improve the existing knowledge for the pathogenicity of P. salmonis we present here a global proteomic profiling of Salmon salar macrophage-like cell cultures infected with P. salmonis LF-89. The proteomic analyses identified several P. salmonis proteins from two temporally different stages of macrophages infection; some of them related to key functions for bacterial survival in other intracellular pathogens. Metabolic differences were observed in early-stage infection bacteria, compared to late-stage infections. Virulence factors related to membrane, LPS and surface component modifications, cell motility, toxins and secretion systems also varied between the infection stages. Pilus proteins, beta-hemolysin and the T6SS were characteristic of the early-infection stage, while fimbria, upregulation of 10 toxins or effector proteins, and the Dot/Icm T4SS were representative of the late-infection stage bacteria. Previously described virulence-related genes in P. salmonis plasmids were identified by proteomic assays during infection in SHK-1 cells, accompanied by an increase of mobile-related elements. By comparing the infected and un-infected proteome of SHK-1 cells, we observed changes in cellular and ROS homeostasis, innate immune response, microtubules and actin cytoskeleton organization and dynamics, alteration in phagosome components, iron transport and metabolism, and amino acids, nucleoside and nucleotide metabolism, together with an overall energy and ATP production alteration. Our global proteomic profiling and the current knowledge of the P. salmonis infection process allowed us to propose a model of the macrophage-P. salmonis interaction.
ARTICLE | doi:10.20944/preprints202009.0089.v1
Subject: Life Sciences, Microbiology Keywords: Pasteurella multocida; antimicrobial resistance genes; antimicrobial susceptibility patterns; swine
Online: 4 September 2020 (07:47:26 CEST)
Forty-eight Pasteurella multocida isolates were recovered from porcine pneumonic lungs collected in Norwestern Spain (2017- 2019). These isolates were characterized for their minimal inhibition concentrations to twelve antimicrobial agents and for the appearance of eight resistance genes: tetA, tetB, blaROB1, blaTEM, ermA, ermC, mphE and msrE. Relevant resistance percentages were shown to teracyclines, sulphamethoxazole/trimethoprim and tiamulin, thus suggesting that P. multocida isolates were mostly susceptible to amoxicillin, ceftiofur, enrofloxacin, florfenicol, marbofloxacin and macrolides. 29.2% of isolates were resistant to more than two antimicrobials. The tetracycline resistance genes (tetA and tetB) were detected in 22.9% of the isolates, but none was positive to both simultaneously; blaROB1 and blaTEM genes were found in one third of isolates but both genes were detected simultaneously in only one isolate. ermC gene was observed in 41.7% of isolates, a percentage that decreased until 22.9% for msrE; finally, ermA was harboured by 16.7% and mphE was not found in any of them. Six clusters were established based on hierarchical clustering analysis on antimicrobial susceptibility for the twelve antimicrobials. Generally, it was unable to foresee the antimicrobial susceptibility pattern for each family and the association of each particular isolate inside the clusters established from the presence or absence of the resistance genes analyzed.
Tue, 1 September 2020
ARTICLE | doi:10.20944/preprints202009.0015.v1
Subject: Life Sciences, Microbiology Keywords: Enzymerhodopsin; Channelrhodopsins; Optogenetics; Two-component system; Cyclase; Phosphodiesterase
Online: 1 September 2020 (11:50:03 CEST)
Light-gated ion channel and ion pump rhodopsins are widely used as optogenetic tools and these can control the electrically excitable cells as: (1) they are a single-component system i.e., their sensor and effector functions are encoded by the 7-transmembrane domains and (2) they show fast kinetics with small dark-thermal recovery time. In cellular signaling, a signal receptor, modulator and effector components are involved for attaining synchronous multicomponent regulation. Optical modulation of this network requires either receptor to effector encoded in a single ORF or direct modulation of the effector domain through bypassing all upstream players. Recently discovered modular rhodopsins like rhodopsin guanine cyclase (RhoGC) and rhodopsin phosphodiesterase (RhoPDE) paves the way to establish proof of concept. Light sensor coupled modular system could be expressed in a precise cell type and which holds great potential in the advancement of optogenetics 2.0. It would enable manipulating entire relevant cell signaling system. Here, we had identified 50 novels modular rhodopsins with variant rhodopsins domain and its diverse cognate signaling cascades encoded in a single ORF, which are associated with specialized functions in the cells. These novel modular algal rhodopsins have been characterized functionality based on their sequence and structural homology with previously characterized rhodopsins. Presented novel modular rhodopsins with various effector domains hold potential to expand optogenetics tool kit to regulate various cellular signaling pathways across the diverse biological model systems.
Mon, 31 August 2020
ARTICLE | doi:10.20944/preprints202008.0727.v1
Subject: Life Sciences, Microbiology Keywords: Preparation 500; horn manure; biodynamic agriculture; keratin; Onygenales
Online: 31 August 2020 (17:40:08 CEST)
Horn manure (Preparation 500) is a product used in the practice of biodynamic agriculture. It is obtained by an underground fermentation of cow faecal material incubated in cow horns for several months. The product is used as spray treatment meant to increase soil fertility. In the present report we analyzed the successional changes in bacterial and fungal communities throughout the process of horn manure maturation by high throughput sequencing of ribosomal 16S (bacterial) and ITS (fungal) gene markers. Marked shifts in the microbial community were seen involving a general decrease from a Firmicutes-dominated material to a product transiently enriched in Proteobacteria and later in Actinobacteria, mostly within the Nocardioidaceae family. In the fungal community evolution, the most abundant taxon in the starting faecal material resulted a member of the Onygenales order, known to specifically degrade keratin. Its abundance in the intestine is explained by the fact that keratin, which is also the structural component of hairs and horns, is found in all epithelial layers, including gut mucosae. This occurrence suggests a link of enzymatic/catabolic nature between manure and horn.
ARTICLE | doi:10.20944/preprints202008.0708.v1
Subject: Life Sciences, Microbiology Keywords: streptococcus suis; transcriptome; ferrous iron; cobalt; RNA sequencing
Online: 31 August 2020 (09:51:43 CEST)
Streptococcus suis is a zoonotic pathogen causing serious infections in both swine and humans. Although metals are essential for life, excess amounts of metals they are toxic to bacteria. when accumulated in excess amounts. Except for zinc, Transcriptome-level data of the mechanisms for resistance to metal-induced toxicity in S. suis are available for no metals other than zinc. have not been investigated from the transcriptome level in S. suis. Herein, we explored the transcriptome-level changes of in S. suis in response to ferrous iron and cobalt toxicity by RNA sequencing. Many A lot of genes were differentially expressed in the presence of excess ferrous iron and cobalt. Most of the genes in response to cobalt toxicity showed the same expression trends as those were expressed in the same trend in response to ferrous iron toxicity. qRT-PCR analysis of the selected genes confirmed the accuracy of RNA sequencing results. Bioinformatics analysis of the differentially expressed genes indicated that ferrous iron and cobalt have similar impacts effects on the cellular processes of S. suis. Treatment with ferrous Ferrous iron treatment resulted in down-regulation of several oxidative stress tolerance-related genes involved in oxidative stress tolerance and up-regulation of the genes in an amino acid ABC transporter operon. Expression of the several genes in the arginine deiminase system was down-regulated in the presence of after ferrous iron and cobalt treatment. Collectively, our results suggested that S. suis alters the expression of a lot of multiple genes to respond to ferrous iron and cobalt toxicity.
Sun, 30 August 2020
ARTICLE | doi:10.20944/preprints202008.0677.v1
Subject: Life Sciences, Microbiology Keywords: Nasal microbiota; Illumina sequencing; nanopore sequencing; 16S rRNA gene; Bacterial species; Corynebacterium
Online: 30 August 2020 (16:04:50 CEST)
Illumina and nanopore sequencing technologies are powerful tools that can be used to determine the bacterial composition of complex microbial communities. In this study, we compared nasal microbiota results at genus level using both Illumina and nanopore 16S rRNA gene sequencing. We also monitored the progression of nanopore sequencing in the accurate identification of species, using pure, single species cultures, and evaluated the performance of the nanopore EPI2ME 16S data analysis pipeline. Fifty-nine nasal swabs were sequenced using Illumina MiSeq and Oxford Nanopore 16S rRNA gene sequencing technologies. In addition, five pure cultures of relevant bacterial species were sequenced with the nanopore sequencing technology. The Illumina MiSeq sequence data were processed using bioinformatics modules present in the Mothur software package. Albacore and Guppy base calling, a workflow in nanopore EPI2ME and an in house developed bioinformatics script were used to analyze the nanopore data. At genus level, similar bacterial diversity profiles were found, and five main and established genera were identified by both platforms. However, probably due to mismatching of the nanopore sequence primers, the nanopore sequencing platform identified Corynebacterium in much lower abundance compared to Illumina sequencing. Further, when using default settings in the EPI2ME workflow, almost all sequence reads that seem to belong to the bacterial genus Dolosigranulum and a considerable part to the genus Haemophilus were only identified at family level. Nanopore sequencing of single species cultures demonstrated at least 88% accurate identification of the species at genus and species level for 4/5 strains tested, including improvements in accurate sequence read identification when the basecaller Guppy and Albacore, and when flowcell versions R9.4 and R9.2 were compared.
Fri, 28 August 2020
REVIEW | doi:10.20944/preprints202008.0635.v1
Subject: Life Sciences, Microbiology Keywords: Antimicrobial resistance; Beta-lactamase gene; Nigeria; Review
Online: 28 August 2020 (11:28:20 CEST)
This review was carried out to identify different beta-lactamase resistance genes reported in published literature from Nigeria and to determine the proportion estimates of the important beta-lactamase resistance genes in Nigeria. Sixty-three (63) articles were included in this review based on the eligibility criteria. All the beta-lactamases reported were detected from the Gram-negative bacteria, most especially from Enterobacteriaceae (n=53). Thirty-six different beta-lactamase genes have been reported from Nigeria. These genes belong to the narrow-spectrum, AmpC, extended-spectrum, and carbapenemase beta-lactamase resistance genes. Eight (8) genes (blaDHA, blaCTXM-1, blaCTXM-14, blaGES-1, blaVEB-1, blaOXA-1, blaOXA-2, and blaTEM-1) were shared between animals and humans, 5 genes (blaSHV-1, blaSHV-2, blaSHV-11, blaSHV-12, and blaNDM-1) were common to both humans and environment while none of the genes was unique to both animals and environment. Four genes including blaCMY, blaTEM-1, blaAmpC, and internationally pandemic blaCTXM-15 gene were unique to animals, humans, and the environment. No carbapenemase gene was reported from animals yet. The pooled proportion estimate of ESBL genes in Nigeria was 31% (95% CI: 26-36%, P<0.0001), while the estimate of blaCTXM-15 gene in Nigeria was 46% (95% CI: 36-57%, P<0.0001). The proportion estimate of AmpC genes was 32% (95% CI: 11-52%, P<0.001), while the estimate for carbapenemases was 8% (95% CI: 5-12%, P<0.001). This study has provided information on the beta-lactamases distribution in Nigeria. This is necessary for a better understanding of molecular epidemiology of clinically important beta-lactamases especially the extended-spectrum beta-lactamases and carbapenemases in Nigeria.
Thu, 27 August 2020
ARTICLE | doi:10.20944/preprints202008.0623.v1
Subject: Life Sciences, Microbiology Keywords: Leptospermum scoparium; Cryptomeria japonica; Mānuka; Sugi; Essential oils; Natural products; Secondary metabolites; Antimicrobials; Gas chromatography – Mass spectrometry
Online: 27 August 2020 (14:13:24 CEST)
This study evaluated the antimicrobial activity of Leptospermum scoparium (Mānuka) and Cryptomeria japonica (Sugi) essential oils and assessed the effect of seasonal chemical variation on the oils’ antimicrobial efficacies. Plate based assays were conducted to elucidate the oils’ spectrum of in vitro antimicrobial activity and to determine the oils’ minimum inhibitory concentrations (MIC) as a measure of antimicrobial efficacy. Gas chromatography – mass spectrometry was adopted to chemically profile oils distilled in different seasons. The resultant compositional information in conjunction with MIC data was used to evaluate the effect of seasonal variation on the oils’ antimicrobial efficacy. Both Mānuka and Sugi essential oils were active against all classes of target microorganisms. However, limited activity was observed against Gram-negative bacteria. The oils displayed consistent chemotypic characteristics regardless of the time of distillation. Nonetheless, there were quantitative differences in compound abundance in both essential oils. Significant differences in the MIC of Sugi essential oil was observed against target microorganisms as a result of seasonal variation in constituent abundances while Mānuka essential oil’s antimicrobial efficacy was unaffected. This study demonstrates that seasonal chemical variation is an important quality assurance parameter to consider for future application of essential oils as antimicrobial agents in consumer products.
ARTICLE | doi:10.20944/preprints202008.0608.v1
Online: 27 August 2020 (09:43:59 CEST)
Bacterial collections are invaluable tools for microbiologists. However, their practical use is compromised by imprecise taxonomical assignation of bacterial strains. This is particularly true for soft rotting plant pathogens of the Pectobacterium genus. To solve this difficulty, we analyzed the taxonomic status of 265 Pectobacterium strains deposited at CIRM-CFBP collection from 1944 to 2020. This collection gathered Pectobacterium strains isolated in 27 countries from 32 plant species representing 17 botanical families or from non-host environments. MLSA approach completed by genomic analysis of 15 strains was performed to update the taxonomic status of these 265 strains. Results showed that the CIRM-CFBP Pectobacterium collection harboured at least one strain of each species to the exception of P. polonicum. Yet, 6 strains could not be assigned to any of the described species and may represent at least two new species. Surprisingly, the P. versatile species, recently described in 2019, is the most prevalent species among CIRM-CFBP strains. Analysis of P. versatile strains revealed that this species is endemic all over the world on various host plants and environments. At the opposite, other species gathered strains isolated from only one botanical family or exclusively from fresh water environment. Our work also revealed new host plants for several Pectobacterium spp.
ARTICLE | doi:10.20944/preprints202008.0604.v1
Subject: Life Sciences, Microbiology Keywords: aerobic mesophilic; black sigatoka; cropping systems; libanga likale; Yangambi 5Km; Litete; gros michel
Online: 27 August 2020 (08:55:23 CEST)
The microorganisms play crucial roles in the cycle of matter and damage the organic substances, sources of electrons, source of carbon, source of energy for their biosynthesis. While dying, the microorganisms contribute on their turn to enrich soil in different composed of the carbon. In this work, we studied the impact of the aerobic mesophiles microorganisms on the black sigatoka of banana in the old secondary forest. The objective was to count and to identify the microbial diversity of the forest ecosystems, as well as to study their impact on the development of the black sigatoka of banana around the forest reserve of Masako. The assessment of the microbial populations has been done in an experimental field according to a device in blocks of Fischer by the method of successive dilutions of coloration of Gram and by the discharge of ascospores. The results showed that the rain season was lower in total microbial biomass (700, 7 colonies) than the subdry season (840,3 colonies). The Bacillus genera have been more represented more than the Coccus genera. The impact of black sigatoka of banana was raised at the cultivar Libanga Likale (40%) and low at Yangambi 5 Km (14%). The distribution of microorganisms in depth in the sub-dry season to the level of surface with vegetation was considerable either 3819, 3. 103 UFC( UNIT FORMAT COLONY) by gram of soil between 0 and 5 cm against 2754,5.103 UFC by gram of soil between 15 and 20 cm. This suggests that the raised number of microorganisms could have positive impact on soil fertility by decreasing the illnesses in this ecosystem.
Tue, 25 August 2020
Subject: Life Sciences, Microbiology Keywords: membrane remodeling; membrane biosynthesis; membrane curvature; phospholipids; inner membrane; lipid biosynthesis
Online: 25 August 2020 (10:03:25 CEST)
Membrane remodeling and phospholipid biosynthesis are normally tightly regulated to maintain the shape and function of cells. Indeed, different physiological mechanisms ensure a precise coordination between de novo phospholipid biosynthesis and modulation of membrane morphology. Interestingly, the overproduction of certain membrane proteins hijack these regulation networks, leading to the formation of impressive intracellular membrane structures in both prokaryotic and eukaryotic cells. The proteins triggering an abnormal accumulation of membrane structures inside the cells (or membrane proliferation) share two major common features: 1) they promote the formation of highly curved membrane domains and 2) they lead to an enrichment in anionic, cone-shaped phospholipids (cardiolipin or phosphatidic acid) in the newly formed membranes. Taking into account the available examples of membrane proliferation upon protein overproduction, together with the latest biochemical, biophysical and structural data, we explore the relationship between protein synthesis and membrane biogenesis. We propose a mechanism for the formation of these non-physiological intracellular membranes that shares similarities with natural inner membrane structures found in α-proteobacteria, mitochondria and some viruses-infected cells, pointing towards a conserved feature through evolution. We hope that the information discussed in this review will give a better grasp of the biophysical mechanisms behind physiological and induced intracellular membrane proliferation, and inspire new applications, either for academia (high-yield membrane protein production and nanovesicle production) or industry (biofuel production and vaccine preparation).
Fri, 21 August 2020
ARTICLE | doi:10.20944/preprints202008.0486.v1
Subject: Life Sciences, Microbiology Keywords: Bacillus subtilis; Bio-surfactants; emulsification index; Hydrocarbons; surface tension.
Online: 21 August 2020 (13:27:24 CEST)
Bio-surfactants are surface-active molecules which are produced by the wide range of microbes including bacteria, fungi, and yeast. This study was conducted to identify bio-surfactants by Bacillus subtilis combined with use of cheap substrates and industrial wastes (Mustard cake, Whey and Soya cake) which are found locally in Nepal. Bacillus subtilis, one of the most potential bio-surfactants producer; was isolated from soil sample of hydrocarbon contaminated site. Isolates were grown in a Minimal Salt Media (MSM) with 10% (v/v) mustard oil cake, whey and soya cake separately. The presence and potential of surfactant was determined by the oil spreading technique, emulsification index (%E24) and surface tension measurement. It was revealed that the surface tensions of cell free extract were 54.41, 60.02 and 56.64 mN/m for from mustard cake, whey and soya cake respectively as compared to distilled water (72.09) at 25oC. The emulsification index values are was found to be highest in engine oil from the bio-surfactant extracted from mustard cake, soya cake and whey respectively. Similarly, mustard oil showed the lowest value of emulsification index. The highest emulsification activity was shown in mustard oil i.e. 1.13 from the cell free extract from mustard oil and lowest in engine oil i.e., 0.07, by the extract from soya cake medium, when measured in spectrophotometer at 540 nm. In conclusion, strain of Bacillus subtilis was found to be the potential surface active agent producers on the mustard oil cake, which can be useful medium for various environmental, food and industrial processes.
Thu, 13 August 2020
REVIEW | doi:10.20944/preprints202008.0291.v1
Subject: Life Sciences, Microbiology Keywords: Advanced Oxidation Process, Antibacterial resistance, Disinfection, Persistence, ROS, Stress response
Online: 13 August 2020 (06:15:17 CEST)
Different water treatment regiments are revealed to have potential in enriching antibiotic resistant bacteria (ARB). Advanced oxidation processes (AOPs) based disinfection techniques have been studied widely in the recent times due to their advantages over conventional treatment methods. However, bacterial response and adaptations against the hostile environments of AOPs is not clearly understood yet. Based on the existing knowledge on the ways in which bacteria surpass the antibiotic treatment, here we propose few important aspects of bacterial adaptation which could be true for AOPs as well since both antibiotics and AOPs generate reactive oxygen species (ROS) during their modes of action. We discuss the plausible role of ROS in the selection of ARB and bacterial heterogeneity as a strategy to bypass the lethal action of AOPs. Understanding bacterial adaptation during disinfection plays a vital role in devising strategies to outclass the bacterial survival. Hence, more importance should be given to such studies in the near future for the successful implementation of AOPs.
Sat, 8 August 2020
ARTICLE | doi:10.20944/preprints202008.0206.v1
Subject: Life Sciences, Microbiology Keywords: tongue microbiome; salivary microbiome; amplicon sequence variant (ASV); operational taxonomical unit (OTU); denoising; DADA2; taxonomic classifier
Online: 8 August 2020 (09:29:46 CEST)
The bacterial composition of oral samples has traditionally been determined by PCR amplicon sequencing of 16S rRNA genes. Recent amplicon sequence variant (ASV)-based analyses of 16S rRNA genes differ from that based on operational taxonomic unit (OTU) clustering in the way it deals with sequences having potential errors. However, little information is available on its application in oral microbiome studies. Here, we conducted ASV-based analysis of oral microbiome samples using QIIME 2. We investigated the optimal parameters for sequence denoising, using DADA2, and found the trimming of the first 20 nucleotides from 5′-end of both paired reads avoided excessive sequence loss during chimera removal. Truncating reads at positions 240–245 allowed the removal of low-quality sequences while maintaining sufficient length to merge matching paired ends. Taxonomic assignment, using the naïve Bayes classifier trained with the V3-V4 region of reference 16S rRNA sequences in the extended human oral microbiome database (eHOMD), resulted in bacterial compositions similar to those of OTU-based analyses. Contrary to OTU-based clustering, ASV-based analysis showed taxonomic abundance at the genus or species level to not differ significantly in tongue microbiomes, regardless of brushing. QIIME 2 can, therefore, be a standard pipeline for ASV-based analysis of oral microbiomes.
Fri, 7 August 2020
CASE REPORT | doi:10.20944/preprints202008.0198.v1
Subject: Life Sciences, Microbiology Keywords: SARS-CoV-2; coinfection; diabetes, bloodstream infection; Candida glabrata; echinocandin resistance; FKS mutation
Online: 7 August 2020 (12:54:12 CEST)
Coinfections with bacteria or fungi may be a frequent complication of COVID-19, although coinfections with Candida species in COVID-19 patients remain rare. We report the 53-day clinical course of a complicated type-2 diabetes patient diagnosed with COVID-19, who developed bloodstream infections initially due to methicillin-resistant Staphylococcus aureus, secondly to multidrug-resistant Gram-negative bacteria, and lastly to a possibly fatal Candida glabrata. Development of FKS-associated pan-echinocandin resistance in the C. glabrata isolated from the patient after 13 days of caspofungin treatment aggravated the situation. The patient died of septic shock shortly before the prospect of receiving potentially effective antifungal therapy. This case emphasizes the importance of early diagnosis and monitoring for antimicrobial drug-resistant coinfections to reduce their unfavorable outcomes in COVID-19 patients.
Wed, 5 August 2020
ARTICLE | doi:10.20944/preprints202008.0120.v1
Subject: Life Sciences, Microbiology Keywords: intestine microbiota; Cattle Egret; Pied Crows; Kinshasa
Online: 5 August 2020 (09:59:45 CEST)
Purpose: Our study focused on Pied Grow and Cattle Egret, two commensal and ubiquitous birds feeding in dumps and frequenting our homes. Our aim was to identify the bacteria that birds bring to our homes and could be a potential risk to Congolese health. Method: We have done bacteriological analyses of bird feces for to explore its gut micriobiota composition. The feces were collected in the uricotelic cloaca by using a swab in 52 Cattle Egrets (Bubulcus ibis) and 23 Pied Crows (Corvus albus) from Kinshasa city. Results: Bacteriological analyses revealed the presence of Proteus vulgaris (3.8%) and Klebsiella pneumoniae (5.8%) on Cattle Egret, Salmonella sp. (8.7%), Klebsiella pneumoniae (8.7%), Pseudomonas aeruginosa (21.7%), Proteus vulgaris (30.4%) on Pied Crow, Citrobacter spp and Escherichia coli (100%) on both Cattle Egret and Pied Crow respectively. Conclusion: The presence of these pathogenic germs, suggesting these commensal and ubiquitous birds may be potential vectors of various Diseases which pose serious health problems in the region.
ARTICLE | doi:10.20944/preprints202008.0106.v1
Subject: Life Sciences, Microbiology Keywords: citrus pectin; lemon; grapefruit; IntegroPectin; flavonoids; citrus terpenes; polyphenols; antimicrobial resistance; Staphylococcus aureus; Pseudomonas aeruginosa
Online: 5 August 2020 (03:34:49 CEST)
Grapefruit and lemon pectin obtained from the respective waste citrus peels via hydrodynamic cavitation in water only are powerful, broad-scope antimicrobial alternatives to antibiotics against Gram-negative and -positive pathogens. Dubbed IntegroPectin, these pectic polymers functionalized with citrus flavonoids and terpenes show superior antimicrobial activity when compared to commercial citrus pectin. Similarly to commercial pectin, lemon IntegroPectin determined ca. 3 log reduction of Staphylococcus aureus cells, while an enhanced activity of commercial citrus pectin was detected in the case of Pseudomonas aeruginosa cells with a minimal bactericidal concentration (MBC) of 15 mg mL-1. Although grapefruit and lemon IntegroPectin share equal MBC in the case of P. aeruginosa cells, grapefruit IntegroPectin shows boosted activity upon exposure of S. aureus cells with a 40 mg mL-1 biopolymer concentration being sufficient to achieve complete killing of the bacterial cells. Insight on the mechanism of action of these biocompatible antimicrobials and their effect on bacterial cells, at the morphological level, were obtained indirectly through Fourier Transform Infrared spectroscopy and directly through scanning electron microscopy. In the era of antimicrobial resistance, these results are of great societal and sanitary relevance as they open new avenues to develop innovative antimicrobials for the treatment of polymicrobial infections unlikely to develop drug resistance.
Tue, 4 August 2020
ARTICLE | doi:10.20944/preprints202008.0084.v1
Online: 4 August 2020 (10:59:54 CEST)
Vibrio is a bacterial genus widely distributed in natural aquatic systems. Some Vibrio species are pathogenic and can cause severe diseases in both marine organisms and humans. Previous studies revealed a link between the current climate change and increased incidence of the Vibrio-associated diseases recently causing sanitary, economic and/or ecological problems worldwide. The conventional culture-based methods (e.g. cultivation of TCBS agar) used to monitor the presence of Vibrio spp. in environmental samples are not always straightforward and can underestimate the number of cells, especially if the microbial population contains a fraction of ‘dormant’ cells (e.g. cells in Viable but not Culturable (VBNC) state). However, this problem can be overcome by using alternative culture-free approaches such as Catalyzed Reporter Deposition-Fluorescence In situ Hybridization (CARD-FISH). To optimize CARD-FISH for efficient and reliable detection of Vibrio spp. in environmental samples, we have used both computer-assisted and experimental approaches. Our results demonstrate that the use of the optimized protocol along with a very specific probe, ViB572a, can offer the high sensitivity and selectivity of CARD-FISH detection of marine vibrios in natural seawater.
Mon, 3 August 2020
REVIEW | doi:10.20944/preprints202008.0065.v1
Subject: Life Sciences, Microbiology Keywords: SARS-CoV-2; SARS-CoV; influenza; pneumonia; respiratory tract infectious diseases
Online: 3 August 2020 (08:44:56 CEST)
The short study implicates few basic similarities of COVID-19 such as diseases origination, symptoms, diagnosis with other relatable viral diseases viz SARS-CoV, common Flu, pneumonia etc. In the present situation, other viral diseases are frequently chaotic and misled with COVID-19 disease because of few clinical features similarities in signs and symptoms and also due to lack of specific diagnostic test. To avoid unnecessary suspects, quarantines of false positive results and to prevent the spread of COVID-19 diseases, the scientific technical research field are highly encourage to implement an efficient, rapid and sophisticated superior test for early stages of infection detection. It will be significantly convenient for physician, laboratory technicians and most importantly the common population facing a psychological disturbance.
ARTICLE | doi:10.20944/preprints202008.0063.v1
Subject: Life Sciences, Microbiology Keywords: raw milk; microbiological safety; microbiological quality; food safety; dairy; MBS method
Online: 3 August 2020 (08:07:03 CEST)
The consumption of dairy products and the dairy industry is one of the main global agro-food sectors for size, economic importance and level of technology. Microbiological quality of pasteurized milk or other milk products is dependent on microbiological quality of raw milk. A variety of microbiological count methods is available for monitoring the hygienic quality of raw milk. Among them, the pour plate method is the official essay for counting the number of colony forming units in milk samples according to ISO 4833-1:2013. The aim of the present study is the validation of the Micro Biological Survey (MBS) method, against the reference plate count method, for the assessment of the microbiological quality of raw milk. This comparative study, performed in collaboration with the “Istituto Zooprofilattico Sperimentale del Lazio e della Toscana M. Aleandri” (IZSLT), demonstrates the accuracy of this alternative method for the determination of total viable bacterial count in cow’s raw milk. The results obtained with the MBS method highlighting its potential as a valid tool for reliable microbiological analysis in dairy industries.
ARTICLE | doi:10.20944/preprints202008.0056.v1
Subject: Life Sciences, Microbiology Keywords: Cornu aspersa mucus; antimicrobial peptides; antibacterial activity; bacterial strains; Pseudomonas aureofaciens AP9; Escherichia coli NBIMCC 8785; Brevibacillus laterosporus strain BT-271; Clostridium perfringens NBIMCC 8615
Online: 3 August 2020 (00:25:22 CEST)
Natural products have long played a major role in medicine and science. The garden snail Cornu aspersa is a rich source of biologically active natural substances which might be an important source for new drugs to treat human disease. Based on our previous studies seven fractions containing compounds with Mw <3 kDa, <10 kDa, <20 kDa, >20 kDa, and between 3-5 kDa, 5-10 kDa, and 10-30 kDa were purified from the mucus of C. aspersa and analyzed by tandem mass spectrometry (MALDI-TOF/TOF). Seventeen novel peptides with potential antibacterial activity have been identified by de novo MS/MS sequencing using tandem mass spectrometry. The different fractions were tested for antibacterial activity against Gram─ (Pseudomonas aureofaciens and Escherichia coli) and Gram+ (Brevibacillus laterosporus) bacterial strains as well anaerobic bacterium Clostridium perfringens. These results revealed that the peptide fractions exhibit a predominant antibacterial activity against B. laterosporus, the fraction with Mw 10 – 30 kDa against E. coli, another peptide fraction <20 kDa against P. aureofaciens, and the protein fraction >20 kDa against the bacterial strain C. perfringens. The discovery of new antimicrobial peptides (AMPs) from natural sources is of great importance for public health due to their effective antimicrobial activities and low resistance rates.
Sat, 25 July 2020
Subject: Life Sciences, Microbiology Keywords: Klebsiella pneumoniae; nonmucoid; O-antigen; outer membrane protein; phage receptor
Online: 25 July 2020 (18:55:02 CEST)
The use of bacteriophage is reemerging as a tool for combatting multi-drug resistant bacterial infections. In our previous study, we showed that colistin resistant carbapenem-resistant Klebsiella pneumoniae (ColR-CRKP) is more susceptible to killing by lytic tailed phages, including ФNJS1 specific for nonmucoid K. pneumoniae. Although we demonstrated that alteration on surface charges of ColR-CRKP promotes phage adherence and infection, the receptor for ФNJS1 was still unknown. In current study, we identified O-antigen was involved in the reversible adsorption, and outer membrane protein (OMP) FepA may be served as one of the irreversible receptors for ФNJS1. We firstly found accelerated reversible phage adsorption to ColR-CRKP cells, and that periodate treatment of bacteria inhibited the phage binding, indicating LPS may be involved in phage reversible adsorption. ФNJS1-resistant bacterial mutants screening revealed that mutants in ∆wecG(mTn5) and ∆wecA(mTn5), two genes responsible for LPS biosynthesis, affected phage adsorption capacity and phage infectivity. The loss of wzyE encoding O-antigen polymerase showed no significant difference in phage adsorption but increased phage infectivity, suggesting the long chain length of O-antigen may also be a barrier for bacteriophage infection. Among four OMP mutants including ∆fepA, ∆fhuA, ∆ompA and ∆ompC, only ∆fepA slowed phage lysis rate, suggesting FepA may be as one of irreversible receptors for ФNJS1. The results are helpful to better understand why ColR-CRKP sensitizes phage infection and to combat multi-drug resistant K. pneumoniae infections in the future.
Fri, 24 July 2020
ARTICLE | doi:10.20944/preprints202007.0579.v1
Subject: Life Sciences, Microbiology Keywords: Tolerance; Persistence; Cross-resistance; Toxin-antitoxin system; PemK/PemI; Klebsiella pneumoniae.
Online: 24 July 2020 (11:46:37 CEST)
Although the failure of antibiotic treatment is normally attributed to resistance, tolerance and persistence display a significant role in the lack of response to antibiotics. Due to the fact that several nosocomial pathogens show a high level of tolerance and/or resistance to chlorhexidine, in this study we analyzed the molecular mechanisms associated with chlorhexidine adaptation in two clinical strains of Klebsiella pneumoniae by phenotypic and transcriptomic studies. These two strains belong to ST258-KPC3 (high-risk clone carrying β-lactamase KPC3) and ST846-OXA48 (low-risk clone carrying β-lactamase OXA48). Our results showed that K. pneumoniae ST258-KPC3CA and ST846-OXA48CA strains exhibited a different behavior under CHLX pressure, adapting to this biocide through resistance and tolerance mechanisms, respectively. Furthermore, the appearance of cross-resistance to colistin was observed in the ST846-OXA48CA strain (tolerant to CHLX), using the broth microdilution method. Interestingly, this ST846-OXA48CA isolate contained a plasmid that encodes a novel type II toxin/antitoxin (TA) system, PemK/PemI. We characterized this PemK/PemI TA system by cloning both genes into the IPTG-inducible pCA24N plasmid, and found their role in persistence and biofilm formation. Accordingly, the ST846-OXA48CA strain showed a persistence biphasic curve in the presence of a chlorhexidine-imipenem combination, and these results were confirmed by the enzymatic assay (WST-1).
Sun, 19 July 2020
ARTICLE | doi:10.20944/preprints202007.0423.v1
Subject: Life Sciences, Microbiology Keywords: Cryptococcus spp; MALDI-TOF MS; peak analysis; in-house library; hierarchical clustering
Online: 19 July 2020 (19:07:20 CEST)
MALDI-TOF (Matrix-Assisted Laser Desorption/Ionization Time-of Flight) is a type of mass spectrometry (MS) that has been widely implemented for the rapid identification of microorganisms over the last decade. The accuracy and flexibility of this method has encouraged researchers to implement the analysis of protein spectra obtained by MALDI-TOF for the discrimination of close-related species and bacterial typing. In this study, a standardized methodology based on the detection of species-specific protein peaks from the spectra obtained with MALDI-TOF is described. The methodology was applied to a collection of Cryptococcus spp. (n=70) previously characterized by Amplified Fragment Length Polymorphism (AFLP) and sequencing of the ITS1-5.8S-ITS2 region. An expanded ad-hoc database was also built for their discrimination with MALDI-TOF. This approach did not allow the discrimination of the interspecies hybrids. However, the performance of peak analysis with the application of the PLS-DA and SVM algorithms in a two-step analysis allowed 96.95% and 96.55% correct discrimination of C. neoformans from the interspecies hybrids, respectively. Besides, PCA analysis prior to SVM provided 98.45% correct discrimination of the 3 analyzed species in a one-step analysis. The method is cost-efficient, rapid and user-friendly. The procedure can also be automatized for an optimized implementation in the laboratory routine.
Fri, 17 July 2020
REVIEW | doi:10.20944/preprints202007.0393.v1
Subject: Life Sciences, Microbiology Keywords: Enterococcus; antibiotic resistance; vancomycin resistance; public health; nosocomial opportunists
Online: 17 July 2020 (15:32:54 CEST)
Enterococci are gastrointestinal commensals whose hardiness allowed them to colonize very diverse environments, including soils, water, food and feed. This ability to overcome adverse conditions makes enterococci problematic once they colonize hospital niches. Together with the malleability of their genomes, the capacity to acquire and disseminate determinants of antibiotic resistance have contributed to convert what was once just another opportunistic pathogen into a first-class clinical problem. This review discusses the dimension of the emergence of enterococcal resistance to key antimicrobial agents, the dissemination of this resistance and its significance in terms of public health, with the aim of raising the awareness to the need to devise and implement monitoring programmes and effective antibiotic usage guidelines.
Sun, 12 July 2020
ARTICLE | doi:10.20944/preprints202007.0265.v1
Subject: Life Sciences, Microbiology Keywords: Lactococcus garvieae; Grey Mullet (Mugil cephalus); Multiplex PCR; Antibiotic Susceptibility
Online: 12 July 2020 (15:41:52 CEST)
Streptococcal infection is a main infectious diseases for farmed grey mullet (Mugil cephalus). This study were to identify spreptococcal species in diseased farmed grey mullet and to investigate differences in susceptibility to 13 antibiotics and in genotypes between the stains from the grey mullet and non-grey mullet. 170 samples from diseased farmed grey mullet were collected from three county in 2013 -2016. Multiplex PCR identified L. garviea (146) as the main pathogen, S. agalactia (9), S. dysgalactiae (19), and double infection (5), but no S. iniae. The prevalence changed annually and differed among three counties. Pulsed-field gel electrophoresis (PFGE) analysis demonstrated identical genotype with an ApaI-digested DNA pattern. Disc diffusion results demonstrated differences in antibiotic susceptibility between the strains from grey mullet (146) and non-grey mullet (30). Almost all strains resisted to clindamycin and all strains were susceptible to six antibiotic in grey mullet and 4 antibiotics in non-grey mullet. The reduced susceptible strains was more in non-grey mullet than grey mullet group. The reduced susceptible strains were observed the highest in 2014 and in Chiayi county and decreased from 2014 to 2016. However, the strains with reduced susceptibility to ceftriaxone, cirpofoxacin, moxifloxacin, tetracycline for human treatment were observed.
Wed, 8 July 2020
REVIEW | doi:10.20944/preprints202007.0151.v1
Subject: Life Sciences, Microbiology Keywords: One Health; Schistosoma mansoni; Giardia duodenalis; Sanitation and Hygiene (WASH); Uganda
Online: 8 July 2020 (11:32:56 CEST)
Both intestinal schistosomiasis and giardiasis are co-endemic throughout many areas of sub-Saharan Africa, significantly impacting the health of millions of children within endemic areas. While giardiasis is not considered a neglected tropical disease, intestinal schistosomiasis is formally grouped within the NTD umbrella and, as such, receives significant advocacy and financial support for large-scale control, annually. Given the many epidemiological similarities between intestinal schistosomiasis and giardiasis, in this review, we critically discuss why disease surveillance and control activities for giardiasis are largely absent within low- and middle-income countries. With advances in new methods of parasite diagnostics and provision of existing anti-parasitic medications, better management of intestinal schistosomiasis and giardiasis co-infection could, not only be better understood but also, more effectively controlled. In this light, we appraise the suitability of a One Health approach for intestinal schistosomiasis, for if adopted more broadly, could also pave a way forward for more inclusive public health actions against giardiasis.
ARTICLE | doi:10.20944/preprints202007.0140.v1
Subject: Life Sciences, Microbiology Keywords: Markerless cassette; Streptococcus pneumoniae; allelic replacement
Online: 8 July 2020 (10:28:29 CEST)
Streptococcus pneumoniae is the causative agent of a multitude of diseases and further study into its pathogenies is vital. The pneumococcus is genetically malleable and several tools are available to manipulate this pathogen. In this study, we attempted to utilize one such tool, the Sweet Janus cassette, to replace the capsule locus with other capsule loci in our strain background and found that the efficiency of allelic replacement was low and the number of revertant false-positive colonies was high. We determined that the capacity to recombine capsule varied by the initial isolated colony, suggesting that frequency of reversion is dependent on the bacterial cell line. Alternative selection markers may further expand the application of Sweet Janus. We created novel cassettes that utilized chlorinated phenylalanine as an alternative counter-selection agent in conjunction with the Janus or Sweet Janus cassette, providing a new dual or triple selection marker. Moreover, we created cassettes that do not require engineered resistance in the background strain, including both single and dual selection markers. We were able to utilize all constructs in allelic replacement of the capsule loci. These novel constructs provide a new means for generating gene deletions in S. pneumoniae that expand experimental applications.
Wed, 1 July 2020
REVIEW | doi:10.20944/preprints202004.0097.v7
Subject: Life Sciences, Microbiology Keywords: convalescent plasma; serology; pathogen reduction technologies; pathogen inactivation; COVID-19; SARS-CoV2
Online: 1 July 2020 (14:12:21 CEST)
Convalescent blood product therapy has been introduced since early 1900s to treat emerging infectious disease based on the evidence that polyclonal neutralizing antibodies can reduce duration of viremia. Recent large outbreaks of viral diseases for whom effective antivirals or vaccines are still lacking has revamped the interest in convalescent plasma as life-saving treatments. This review summarizes historical settings of application, and surveys current technologies for collection, manufacturing, pathogen inactivation, and banking, with a focus on COVID-19.
Sun, 21 June 2020
SHORT NOTE | doi:10.20944/preprints202006.0259.v1
Online: 21 June 2020 (11:01:58 CEST)
The detection of SARS-Cov-2 in the sewage and water resources has increased the awareness among the people about the possibility survival of SARS-Cov-2 in the environment and the potential to transmit into the human through food chain or water resources. Moreover, the surface contaminated by the virus need to be disinfected frequently by using an effective disinfectant, the current chapter discussed the efficiency of the most traditional treatment process of the sewage and wastewater, and their role in the elimination of the virus as well as the sterility assurance level concept. Moreover, the chemical disinfectant used currently and their temporary efficiency has been reviewed.
Thu, 18 June 2020
Subject: Life Sciences, Microbiology Keywords: skin microbiome; skin microbiome biodiversity; biodiversity; skin ecosystem; skin allergy epidemic; benchmark skin health values; skin bacteria; 21st century skin ailments; measure skin health; healthy skin ecosystem; healthy skin bacteria; damaged skin bacteria;
Online: 18 June 2020 (12:40:57 CEST)
A catastrophic loss of microbial biodiversity on the skin has led to alarming increase in the prevalence of allergies and long-term damage to the skin, which could also have damaging knock on effects to overall health. This study uses 50 human participants, to obtain an average (benchmark) value for the biodiversity of ‘healthy’ western skin, which is crucial in updating our 2017 skin health measuring mechanism to use standardised methodology. Previous work with a larger sample size was unsatisfactory for use as a benchmark due to its use of different and outdated diversity indices. We also investigated the effect of age and sex, two known skin microbiome affecting factors. Although no statistical significance is seen for age- and sex- related changes in diversity, there appear to be changes related to age which elaborates on previous work which used larger, more general age ranges. Our study indicates adults age 28-37 have highest diversity, and age 48-57 the lowest. Crucially, because of this study we are now able to update the skin health measuring mechanism from our 2017 work. This will aid diagnostic assessment of susceptibility to cutaneous conditions or diseases, and treatment. Testing any human subject will be rapidly improved by obtaining future benchmark diversity values for any age, sex, body site and area of residence, to which they can be compared. This improvement means we can also more accurately investigate the ultimate question: What factors in the western world are a main cause of the skin allergy epidemic? This could lead to future restriction of certain synthetic chemicals or products found to be particularly harmful to the skin.
Fri, 12 June 2020
ARTICLE | doi:10.20944/preprints202006.0141.v1
Subject: Life Sciences, Microbiology Keywords: Wolbachia; tick cell line; Ctenocephalides; flea; Malaysia; in vitro culture; phylogeny
Online: 12 June 2020 (04:51:00 CEST)