Environmental Microbiology

Wed, 11/11/2020 - 22:09
Amphiphilic siderophores including amphibactins are the most abundant siderophores in oceans. Genes putatively encoding the amphibactin system were proposed in some bacteria and homologues of these genes are particulary abundant in multiple bacterial lineages inhabitant of low‐iron seawater. However, since no defective mutant strains in any of these genes were studied to date, their role in...
Mon, 10/19/2020 - 22:09
Wheat scab, mainly caused by Fusarium graminearum, can decrease wheat yield and grain quality. Chemical pesticides are currently the main control method but have an inevitable negative consequence on the environment and in food safety. This research studies a promising substitute, Streptomyces pratensis S10, which was isolated from tomato leaf mold and shows a significant inhibition effect on F....
Tue, 10/13/2020 - 22:09
MerF, a proposed bacterial mercury transporter, was surprisingly found to play key roles in the flagellum biogenesis and motility but not mercuric resistance of the deep‐sea bacterium Pseudomonas stutzeri 273 in our previous study. However, the mechanism behind this interesting discovery has not been elucidated. Here, we firstly applied the combined transcriptomic and proteomic analysis to the P...
Thu, 09/17/2020 - 22:10
Cadmium (Cd) is a common toxic heavy metal in the environment, and bacteria have evolved different strategies against Cd‐toxicity. Here we found that marine bacterium Bacillus sp. 98 could significantly alleviate Cd‐toxicity by recruiting calcium (Ca) for reducing excessive intracellular nitric oxide (NO) and enhancing iron acquisition. To investigate the underlying mechanisms, mass spectrometry‐...
Fri, 09/04/2020 - 22:10
To assess the comparability between taxonomic identification methods for phytoplankton, multiple approaches were used to characterize phytoplankton community composition within the Neuse River Estuary (NRE), North Carolina. Small subunit 18S rRNA gene (18S) sequencing and accessory pigment analysis displayed similar trends, indicating chlorophytes were the dominant microalgal group during most of...
Fri, 09/04/2020 - 22:10
Vibrio cholerae isolates responsible for cholera pandemics represent only a small portion of the diverse strains belonging to this species. Indeed, most V. cholerae are encountered in aquatic environments. To better understand the emergence of pandemic lineages, it is crucial to discern what differentiates pandemic strains from their environmental relatives. Here, we studied the interaction of...
Sat, 08/29/2020 - 22:11
The human pathogen Vibrio cholerae serves as a model organism for many important processes ranging from pathogenesis to natural transformation, which has been extensively studied in this bacterium. Previous work has deciphered important regulatory circuits involved in natural competence induction as well as mechanistic details related to its DNA acquisition and uptake potential. However, since...
Mon, 08/24/2020 - 21:26
Microbial ecology and activity in wine production influences grapevine health and productivity, conversion of sugar to ethanol during fermentation, wine aroma, wine quality and distinctiveness. Fungi in the vineyard ecosystem are not well described. Here, we characterized the spatial and temporal dynamics of fungal communities associated with the grapevine (grapes, flowers, leaves, and roots) and...
Thu, 08/20/2020 - 22:09
Bacillus cereus is a ubiquitous endospore‐forming bacterium, which mainly affects humans as a food‐borne pathogen. B. cereus can contaminate groundwater used to irrigate food crops. Here, we examined the ability of the emetic strain B. cereus F4810/72 to survive abiotic conditions encountered in groundwater. Our results showed that vegetative B. cereus cells rapidly evolved in a mixed population...
Thu, 08/20/2020 - 22:09
Mitogen‐activated protein kinase (MAPK) cascades are highly conserved in eukaryotic cells and known to play crucial roles in the regulation of various cellular processes. However, compared with kinase‐mediated phosphorylation, dephosphorylation catalyzed by phosphatases has not been well characterized in filamentous fungi. In this study, we identified five MAPK pathway‐related phosphatases (Msg5...
Thu, 08/20/2020 - 22:09
Heavy metal is one of the major factors threatening the survival of microorganisms. Here, a deep‐sea bacterium designated Idiomarina sp. OT37‐5b possessing strong cadmium (Cd) tolerance was isolated from a typical hydrothermal vent. Both Cd‐resistance and removal efficiency of Idiomarina sp. OT37‐5b were significantly promoted by the supplement of cysteine and meanwhile large amount of CdS...
Wed, 08/19/2020 - 22:10
Polycyclic aromatic hydrocarbons (PAHs) are widespread and harmful contaminants and are more persistent under anaerobic conditions. The bioremediation of PAHs in anaerobic zones has been enhanced by treating the contamination with nitrate, which is thermodynamically favourable, cost‐effective, and highly soluble. However, anaerobic PAHs biotransformation processes that employ nitrate as an...
Mon, 08/17/2020 - 22:10
The dissemination and abundances of Vibrio species in aquatic environments are of interest, as some species cause emerging diseases in humans and in aquatic organisms like fish. It is suggested that Vibrio cholerae non‐O1 infections of Plecoglossus altivelis (‘ayu’) were spread to various parts of Japan through the annual transplantation of juvenile fish. To investigate this, we used genome‐aided...
Wed, 08/12/2020 - 22:09
Lysobacter enzymogenes is a nonflagellated, soil proteobacterium that secretes a diffusible antibiotic known as heat‐stable antifungal factor (HSAF) to kill nearby fungi for food. The genome of the model strain OH11 encodes a homologous Wsp system, which is generally deployed by flagellated bacteria to achieve flagella‐dependent outputs via a c‐di‐GMP‐FleQ complex, in which c‐di‐GMP is a...
Wed, 08/12/2020 - 22:09
As filter‐feeders, bivalve molluscs accumulate Vibrio into edible tissues. Consequently, an accurate assessment of depuration procedures and the characterization of the persistent Vibrio community in depurated shellfish represent a key issue to guarantee food safety in shellfish products. The present study investigated changes in the natural Vibrio community composition of the Ruditapes...
Mon, 08/10/2020 - 22:09
Research on the initial phage‐host interaction has been conducted on a limited repertoire of phages and their cognate receptors, such as phage λ and the Escherichia coli LamB (EcLamB) protein. Apart from phage λ, little is known about other phages which target EcLamB. Here, we developed a simple method for isolating novel environmental phages in a predictable way, i.e. isolating phages which...
Wed, 07/15/2020 - 22:10
Polycyclic aromatic hydrocarbons (PAHs) are among the most persistent xenobiotic compounds, with high toxicity effects. Mycoremediation with halophilic Aspergillus sydowii was used for their removal from a hypersaline medium (1 M NaCl). A. sydowii used PAHs as sole carbon sources, resulting in the removal of up to 90% for both PAHs (benzo [a] pyrene (BaP) and phenanthrene (Phe)) after 10 days....
Wed, 07/01/2020 - 22:09
The development of sustainable agriculture and the increasing antibiotic resistance of human pathogens call for novel antimicrobial compounds. Here, we describe the extraction and characterization of a class of cationic circular lipopeptides, for which we propose the name relacidines, from the soil bacterium Brevibacillus laterosporus MG64. Relacidines are composed of a fatty acid side chain (4‐...
Sat, 06/27/2020 - 22:08
The type VI nanomachine is critical for Vibrio cholerae to establish infections and to thrive in niches co‐occupied by competing bacteria. The genes for the type VI structural proteins are encoded in one large and two small auxiliary gene clusters. VCA0117 (VasH) – a σ54‐transcriptional activator – is strictly required for functionality of the type VI secretion system since it controls production...
Mon, 06/22/2020 - 22:09
Vibrio vulnificus is a zoonotic pathogen able to cause diseases in humans and fish that occasionally result in sepsis and death. Most reviews about this pathogen (including those related to its ecology) are clearly biased towards its role as a human pathogen, emphasizing its relationship with oysters as its main reservoir, the role of the known virulence factors as well as the clinic and the...
Fri, 06/19/2020 - 22:08
Wetlands are common sites of active Hg methylation by anaerobic microbes; however, the amount of methylmercury produced varies greatly, as Hg methylation is dependent upon both the availability of Hg and the composition and activity of the microbial community involved. In this study, we identified the major microbial guilds responsible for Hg methylation along a trophic gradient composed of two...
Tue, 06/09/2020 - 22:09
With the rapid increase of aquaculture contributing to sustainable food security, comes the need to better understand seafood associated diseases. One of the major aquatic bacterial genera responsible for human infections from seafood is Vibrio, especially from oysters. Currently, in vivo study of bacterial interactions within oysters is limited by the inability to promote high‐level uptake of...
Tue, 06/09/2020 - 22:09
In warm regions, agricultural fields are occupied by complex Aspergillus flavus communities composed of isolates in many vegetative compatibility groups (VCGs) with varying abilities to produce highly toxic, carcinogenic aflatoxins. Aflatoxin contamination is reduced with biocontrol products that enable atoxigenic isolates from atoxigenic VCGs to dominate the population. Shifts in VCG frequencies...
Wed, 06/03/2020 - 03:27
Listeria monocytogenes is a foodborne pathogen causing systemic infection with high mortality. To allow efficient tracing of outbreaks a clear definition of the genomic signature of a cluster of related isolates is required, but lineage specific characteristics call for a more detailed understanding of evolution. In our work we used core genome MLST (cgMLST) to identify new outbreaks combined to...
Fri, 05/29/2020 - 03:26
Lake and adjoining river ecosystems are ecologically and economically valuable and are heavily threatened by anthropogenic activities. Determining the inherent capacity of ecosystems for polycyclic aromatic hydrocarbon (PAH) biodegradation can help quantify environmental impacts on the functioning of ecosystems, especially on that of the microbial community. Here, PAH biodegradation potential was...
Sun, 05/24/2020 - 03:24
Antibiotic‐resistant Vibrio alginolyticus poses a big challenge to human health and food safety. It's urgently needed to understand the mechanisms underlying antibiotic resistance to develop effective approaches for the control. Here we explored the metabolic difference between gentamicin‐resistant V. alginolyticus (VA‐RGEN) and gentamicin‐sensitive V. alginolyticus (VA‐S), and found that the...
Thu, 05/21/2020 - 03:27
To identify the free‐living amoeba (FLA) and amoeba resistant bacteria (ARB) accumulated in zebra mussels and in the water in which they are found, mussels were collected at two locations in the Ebro river basin (North East Spain). Free‐living amoebas and bacteria were isolated from mussel extracts and from natural water. PCR techniques were used to identify the FLAs and endosymbiont bacteria (...
Tue, 05/19/2020 - 03:25
Soil microbial communities are often not resistant to the impact caused by microbial invasions, both in terms of structure and functionality, but it remains unclear whether these changes persist over time. Here we used 3 strains of Escherichia coli O157:H7 (E. coli O157:H7), a species used for modelling bacterial invasions, to evaluate the resilience of the bacterial communities from four Chinese...
Tue, 05/19/2020 - 03:25
Enterotoxigenic Escherichia coli (ETEC) cause acute secretory diarrhea in pigs, posing a great economic loss to swine industry. This study analyzed the prevalence and genetic characteristics of prophages from 132 ETEC isolates from symptomatic pigs to determine their potential for spreading antibiotic resistance. A total of 1105 potential prophages were identified, and the distribution of the...
Tue, 05/05/2020 - 03:25
In livestock production, antibiotics are used to promote animal growth, control infections and thereby increase profitability. This practice has led to the emergence of multi‐resistant bacteria such as Salmonella, of which some serovars are disseminated in the environment. The objective of this study is to evaluate microcin J25 as an inhibitor of Salmonella enterica serovars of various origins...
Tue, 05/05/2020 - 03:25
Environmental monitoring of bacteria using phage‐based biosensors has been widely developed for many different species. However, there are only a few available methods to detect specific bacteriophages in raw environmental samples. In this work, we developed a simple and efficient assay to rapidly monitor the phage content of a given sample. The assay is based on the bistable expression of the...
Tue, 04/28/2020 - 03:24
Trebouxia sp. TR9 and Coccomyxa simplex are desiccation‐tolerant microalgae with flexible cell walls, which undergo species‐specific remodelling during dehydration‐rehydration (D/R) due to their distinct ultrastructure and biochemical composition. Here, we tested the hypothesis that extracellular polysaccharides excreted by each microalga could be quantitatively and/or qualitatively modified by D...
Tue, 04/28/2020 - 03:24
The bacterium Vibrio cholerae is a natural inhabitant of aquatic ecosystems across the planet. V. cholerae serogroups O1 and O139 are responsible for cholera outbreaks in developing countries accounting for 3–5 million infections worldwide and 28.800–130.000 deaths per year according to World Health Organization. In contrast, V. cholerae serogroups other than O1 and O139, also designated as V....
Thu, 04/23/2020 - 03:22
Vibrio cholerae can enter a viable but non‐culturable (VBNC) state when it encounters unfavorable environments; VBNC cells serve as important reservoirs and still pose threats to public health. The genetic regulation of V. cholerae entering its VBNC state is not well understood. Here, we show a confrontation strategy adapted by V. cholerae O1 in which it utilizes a quorum sensing (QS) system to...
Thu, 04/16/2020 - 03:18
In Saccharomyces cerevisiae, vacuolar H+‐ATPase (V‐ATPase) involved in the regulation of intracellular pH homeostasis has been shown to be important for tolerances to cadmium, cobalt, and nickel. However, molecular mechanism underlying the protective role of V‐ATPase against these metals remains unclear. In this study, we show that cadmium, cobalt, and nickel disturbed intracellular pH balance by...
Wed, 04/15/2020 - 03:17
Emergence and expansion of frequent multidrug‐resistant (MDR) major Salmonella clones/serotypes has been a significant threat in the last years. Metal compounds, such as copper, commonly used in animal‐production settings, have been pointed out as possible contributors for the selection of such strains/clones. However, the scarcity of studies limits our understanding of the impact of other metal...
Tue, 04/14/2020 - 03:18
Genetic variation in a pathogen, including the causative agent of salmonellosis, Salmonella enterica, can occur as a result of eco‐evolutionary forces triggered by dissimilarities of ecological niches. Here, we applied comparative genomics to study 90 antimicrobial resistant (AMR) S. enterica isolates from bovine and human hosts in New York state and Washington state to understand host‐ and...
Tue, 04/07/2020 - 03:30
Reactive oxygen species (ROS) induce the synthesis of a myriad of secondary metabolites, including aflatoxins. It raises significant concern as it is a potent environmental contaminant. In Aspergillus flavus (A. flavus), antioxidant enzymes link ROS stress response with coordinated gene regulation of aflatoxin biosynthesis. In this study, we characterized the function of a core component of the...
Tue, 04/07/2020 - 03:30
The second messenger cyclic di‐AMP (c‐di‐AMP) is essential for growth of many bacteria because it controls osmolyte homeostasis. c‐di‐AMP can regulate the synthesis of potassium uptake systems in some bacteria and also directly inhibits and activates potassium import and export systems, respectively. Therefore, c‐di‐AMP production and degradation have to be tightly regulated depending on the...
Thu, 04/02/2020 - 03:16
The genome of Vibrio cholerae, the etiological agent of cholera, is an exception to the single chromosome rule found in the vast majority of bacteria and has its genome partitioned between two unequally sized chromosomes. This unusual two‐chromosome arrangement in V. cholerae has sparked considerable research interest since its discovery. It was demonstrated that the two chromosomes could be...
Tue, 03/31/2020 - 03:18
Bacteria constantly experience changes to their external milieu and need to adapt accordingly to ensure their survival. Certain bacteria adapt by means of cellular differentiation, resulting in the development of a specific cell type that is specialized for life in a distinct environment. Furthermore, to understand how bacteria adapt, it is essential to appreciate the significant changes that...
Mon, 03/23/2020 - 03:19
Many Listeria species including L. monocytogenes contain the pathway for the biosynthesis of protocatechuate from shikimate and quinate. The qui1 and qui2 operons within these Listeria spp. encode enzymes for this pathway. The diversion of shikimate pathway intermediates in some Listeria species to produce protocatechuate suggests an important biological role for this compound to these organisms...
Sat, 03/14/2020 - 03:17
Bacteria in nature often encounter non‐antibiotic antibacterials (NAAs), such as disinfectants and heavy metals, and they can evolve resistance via mechanisms that are also involved in antibiotic resistance. Understanding whether susceptibility to different types of antibacterials is non‐randomly associated across natural and clinical bacteria is therefore important for predicting the spread of...
Thu, 03/05/2020 - 03:19
The Type VI Secretion System (T6SS) is a proteinaceous weapon used by many Gram‐negative bacteria to deliver toxins into adjacent target cells. Vibrio cholerae, the bacterium responsible for the fatal water‐borne cholera disease, uses the T6SS to evade phagocytic eukaryotes, cause intestinal inflammation, and compete against other bacteria with toxins that disrupt lipid membranes, cell walls and...
Wed, 03/04/2020 - 03:29
Fresh fruits and vegetables have numerous benefits to human health. Unfortunately, their consumption is increasingly associated with food‐borne diseases, Salmonella enterica being their most frequent cause in Europe. Agricultural soils were postulated as reservoir of human pathogens, contributing to the contamination of crops during the growing period. Since the competition with the indigenous...
Tue, 03/03/2020 - 03:16
The antibiotic‐resistant bacteria (ARB) and antibiotic‐resistant genes (ARGs) in human gut microbiota have significant impact on human health. Whilst high throughput metagenomic sequencing reveals genotypes of bacteria communities, the functionality, phenotype and heterogeneity of human gut microbiota are still elusive. In this study, we applied Raman microscopy with deuterium isotope probing (...
Tue, 03/03/2020 - 03:16
Sea level rise and the anthropogenic warming of the world's oceans is not only an environmental tragedy, but these changes also result in a significant threat to public health. Along with coastal flooding and the encroachment of saltwater farther inland comes an increased risk of human interaction with pathogenic Vibrio species, such as Vibrio cholerae, V. vulnificus and V. parahaemolyticus. This...
Tue, 02/25/2020 - 03:19
Mercury (Hg) is a highly toxic and widely distributed heavy metal which some Bacteria and Archaea detoxify by the reduction of ionic Hg (Hg[II]) to the elemental volatile form, Hg(0). This activity is specified by the mer operon. The mer operon of the deeply‐branching thermophile Thermus thermophilus HB27 encodes for, an O‐acetyl‐L‐homoacetylserine sulfhydrylase (Oah2), a transcriptional...
Fri, 01/24/2020 - 03:16
Populations of the bacterium Vibrio cholerae consist of dozens of distinct lineages, with primarily (but not exclusively) members of the pandemic generating (PG) lineage capable of causing the diarrheal disease cholera. Assessing composition and temporal dynamics of such populations requires extensive isolation efforts and thus only rarely covers large geographic areas or timeframes exhaustively...
Tue, 12/24/2019 - 03:16
Vibrio cholerae is a waterborne bacterium responsible for worldwide outbreaks of acute and fatal cholera. Recently, small regulatory RNAs (sRNAs) have become increasingly recognized as important regulators of virulence gene expression in response to environmental signals. In this study, we determined that two component system EnvZ/OmpR was required for intestinal colonization in V. cholerae O1 EI...

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