Applied and Environmental Microbiology

Wed, 01/20/2021 - 10:01
Pyridoxal 5'-phosphate (PLP) is the biologically active form of vitamin B6, essential for cellular function in all domains of life. In many organisms, such as Salmonella enterica serovar Typhimurium and Escherichia coli, this cofactor can be synthesized de novo or salvaged from B6 vitamers in the environment. Unexpectedly, S. enterica strains blocked in PLP biosynthesis were able to use exogenous...
Wed, 01/20/2021 - 10:01
N-Acetylmuramoyl-l-alanine amidases are periplasmic hydrolases that cleave the amide bond between N-acetylmuramic acid and alanine in peptidoglycan (PG). Unlike many Gram-negative bacteria that encode redundant periplasmic amidases, Vibrio fischeri appears to encode a single protein that is homologous to AmiB of Vibrio cholerae. We screened a V. fischeri transposon mutant library for strains...
Wed, 01/20/2021 - 10:01
Salmonella spp. are resilient bacterial pathogens in low-moisture foods. There has been a general lack of understanding of critical factors contributing to the enhanced thermal tolerance of Salmonella spp. in dry environments. In this study, we hypothesized that the moisture content (XW) of bacterial cells is a critical intrinsic factor influencing the resistance of Salmonella spp. to thermal...
Wed, 01/20/2021 - 10:01
Significant knowledge gaps exist in our understanding of Campylobacter jejuni contamination of the poultry production continuum. Microbiological surveillance and genotypic characterization were undertaken on C. jejuni isolates longitudinally recovered from three poultry farms (weekly samples), the abattoir at which birds were processed, and at retail over a 542-day period in southwestern Alberta...
Wed, 01/20/2021 - 10:01
Genetic recombination plays a pivotal role in the appearance of human norovirus recombinants that cause global epidemics. However, the factors responsible for the appearance of these recombinants remains largely unknown. In this study, we revealed a selective pressure that restricts parental combinations leading to the emergence of norovirus recombinants. To investigate traces of emerging novel...
Wed, 01/20/2021 - 10:01
Rickettsia buchneri is the principal symbiotic bacterium of the medically significant tick Ixodes scapularis. This species has been detected primarily in the ovaries of adult female ticks and is vertically transmitted, but its tissue tropism in other life stages and function with regard to tick physiology is unknown. In order to determine the function of R. buchneri, it may be necessary to...
Wed, 01/20/2021 - 10:01
Despite recent advances in Salmonella-sprout research, little is known about the relationship between Salmonella and the sprout microbiome during sprouting. Sprout spent irrigation water (SSIW) provides an informative representation of the total microbiome of this primarily aquaponic crop. This study was designed to characterize the function and taxonomy of the most actively transcribed genes in...
Wed, 01/20/2021 - 10:01
Fluorescent Pseudomonas spp. producing the antibiotic 2,4-diacetylphloroglucinol (DAPG) are ecologically important in the rhizosphere, as they can control phytopathogens and contribute to disease suppression. DAPG can also trigger a systemic resistance response in plants and stimulate root exudation and branching as well as induce plant-beneficial activities in other rhizobacteria. While studies...
Wed, 01/20/2021 - 10:01
Vibrio parahaemolyticus is the most common cause of seafood-borne illness reported in the United States. The draft genomes of 132 North American clinical and oyster V. parahaemolyticus isolates were sequenced to investigate their phylogenetic and biogeographic relationships. The majority of oyster isolate sequence types (STs) were from a single harvest location; however, four were identified from...
Tue, 01/05/2021 - 10:01
The occurrence of viable-but-nonculturable (VBNC) bacteria poses a potential risk to food safety due to failure in conventional colony detection. In this study, induction of VBNC Staphylococcus aureus was conducted by exposure to an atmospheric-pressure air dielectric barrier discharge-nonthermal-plasma (DBD-NTP) treatment with an applied energy of 8.1 kJ. The stress resistance profiles and...
Tue, 01/05/2021 - 10:01
Subcutaneous vaccination of cattle for enterohemorrhagic Escherichia coli O157:H7 reduces the magnitude and duration of fecal shedding, but the often-required, repeated cattle restraint can increase costs, deterring adoption by producers. In contrast, live oral vaccines may be repeatedly administered in feed, without animal restraint. We investigated whether oral immunization with live stx-...
Tue, 01/05/2021 - 10:01
Rhizodegradation is a promising cleanup technology where microorganisms degrade soil contaminants in the rhizosphere. A symbiotic relationship is expected to occur between plant roots and soil microorganisms in contaminated soils that enhances natural microbial degradation. However, little is known about how different initial microbiotas influence the rhizodegradation outcome. Recent studies have...
Tue, 01/05/2021 - 10:01
The initial steps of Salmonella pathogenesis involve adhesion to and invasion into host epithelial cells. While well-studied for Salmonella enterica serovar Typhimurium, the factors contributing to this process in other, host-adapted serovars remains unexplored. Here, we screened clinical isolates of serovars Gallinarum, Dublin, Choleraesuis, Typhimurium, and Enteritidis for adhesion to and...
Tue, 01/05/2021 - 10:01
Bakanae disease, caused by Fusarium fujikuroi, is an economically important seed-borne disease of rice. F. fujikuroi is horizontally transmitted to rice flowers and vertically transmitted to the next generation via seeds. The fungus induces typical symptoms such as abnormal tissue elongation and etiolation. Sanitation of seed farms and seed disinfection are the only effective means to control...
Tue, 01/05/2021 - 10:01
Prodigiosin (PG), a red linear tripyrrole pigment normally secreted by Serratia marcescens, has received attention for its reported immunosuppressive, antimicrobial, and anticancer properties. Although several genes have been shown to be important for prodigiosin synthesis, information on the regulatory mechanisms behind this cellular process remains limited. In this work, we identified that the...
Tue, 01/05/2021 - 10:01
Despite the wide-ranging proscription of hexavalent chromium, chromium(VI) remains among the major polluting heavy metals worldwide. Aerobic methane-oxidizing bacteria are widespread environmental microorganisms that can perform diverse reactions using methane as the feedstock. The methanotroph Methylococcus capsulatus Bath, like many other microorganisms, detoxifies chromium(VI) by reduction to...
Fri, 12/18/2020 - 10:01
Methomyl {bis[1-methylthioacetaldehyde-O-(N-methylcarbamoyl)oximino]sulfide} is a highly toxic oxime carbamate insecticide. Several methomyl-degrading microorganisms have been reported so far, but the role of specific enzymes and genes in this process is still unexplored. In this study, a protein annotated as a carbamate C-N hydrolase was identified in the methomyl-degrading strain Aminobacter...
Fri, 12/18/2020 - 10:01
A reliable and standardized classification of Listeria monocytogenes is important for accurate strain identification during outbreak investigations. Current whole-genome sequencing (WGS)-based approaches for strain characterization are either difficult to standardize, rendering them less suitable for data exchange, or are not freely available. Thus, we developed a portable and open-source tool,...
Fri, 12/18/2020 - 10:01
Listeria monocytogenes is a foodborne pathogen that causes high rates of hospitalization and mortality in people infected. Contamination of fresh, ready to eat produce by this pathogen is especially troubling because of the ability of this bacterium to grow on produce under refrigeration temperatures. In this study, we created a library of over 8,000 plant phyllosphere-associated bacteria and...
Fri, 12/18/2020 - 10:01
Shiga toxin-producing Escherichia coli (STEC) is a foodborne pathogen that has a significant impact on public health, with strains possessing the attachment factor intimin referred to as enterohemorrhagic E. coli (EHEC) and associated with life-threatening illnesses. Cattle and beef are considered typical sources of STEC, but their presence in pork products is a growing concern. Therefore,...
Fri, 12/18/2020 - 10:01
Environmental sanitation in food manufacturing plants promotes food safety and product microbial quality. However, the development of experimental models remains a challenge due to the complex nature of commercial cleaning processes, which include spraying water and sanitizer on equipment and structural surfaces within manufacturing space. Although simple in execution, the physical driving forces...
Fri, 12/18/2020 - 10:01
Current approaches used for dose-response modeling of low-dose exposures of pathogens rely on assumptions and extrapolations. These models are important for quantitative microbial risk assessment of food. A mechanistic framework has been advocated as an alternative approach for evaluating dose-response relationships. The objectives of this study were to investigate the invasion behavior of...
Fri, 12/18/2020 - 10:01
In recent years, community-associated Clostridium difficile infection (CA-CDI) has emerged as a significant health problem, accounting for ~50% of all CDI cases. We hypothesized that the home garden environment could contribute to the dissemination of C. difficile spores in the community and investigated 23 homes in 22 suburbs of Perth, Western Australia. We identified a high prevalence of...
Wed, 11/25/2020 - 10:01
Infections by A/H5 and A/H7 avian influenza viruses (AIVs) can cause acute disease and are therefore notifiable in poultry and wild birds. During winter 2015-2016, several cases of infection caused by highly pathogenic (HP) AIVs belonging to the A/H5N1, A/H5N2, and A/H5N9 subtypes were detected in southwestern France. Throughout winter 2016-2017, several cases of infections caused mainly by A/...
Wed, 11/25/2020 - 10:01
The third E. coli and the Mucosal Immune System (ECMIS) meeting was held at Ghent University in Belgium from 2 to 5 June 2019. It brought together an international group of scientists interested in mechanisms of colonization, host response, and vaccine development. ECMIS distinguishes itself from related meetings on these enteropathogens by providing a greater emphasis on animal health and...
Wed, 11/25/2020 - 10:01
Influent wastewater and effluent wastewater at the Rya treatment plant in Gothenburg, Sweden, were continuously monitored for enteric viruses by quantitative PCR (qPCR) during 1 year. Viruses in effluent wastewater were also identified by next-generation sequencing (NGS) in samples collected during spring, early summer, and winter. Samples of incoming wastewater were collected every second week....
Wed, 11/25/2020 - 10:01
Hospital wastewater is an increasingly recognized reservoir for resistant Gram-negative organisms. Factors involved in establishment and persistence of Klebsiella pneumoniae carbapenemase-producing organisms (KPCOs) in hospital wastewater plumbing are unclear. This study was conducted at a hospital with endemic KPCOs linked to wastewater reservoirs and robust patient perirectal screening for...
Wed, 11/25/2020 - 10:01
Campylobacter is among the most common causes of gastroenteritis worldwide. Campylobacter jejuni and Campylobacter coli are the most common species causing human disease. DNA sequence-based methods for strain characterization have focused largely on C. jejuni, responsible for 80 to 90% of infections, meaning that C. coli epidemiology has lagged behind. Here, we have analyzed the genome of 450 C....
Wed, 11/25/2020 - 10:01
Natural attenuation of heavy metals occurs via coupled microbial iron cycling and metal precipitation in creeks impacted by acid mine drainage (AMD). Here, we describe the isolation, characterization, and genomic sequencing of two iron-oxidizing bacteria (FeOB) species: Thiomonas ferrovorans FB-6 and Thiomonas metallidurans FB-Cd, isolated from slightly acidic (pH 6.3), Fe-rich, AMD-impacted...
Wed, 11/25/2020 - 10:01
Enterohemorrhagic Escherichia coli (EHEC) causes serious foodborne disease worldwide. It produces the very potent Shiga toxin 2 (Stx2). The Stx2-encoding genes are located on a prophage, and production of the toxin is linked to the synthesis of Stx phages. There is, currently, no good treatment for EHEC infections, as antibiotics may trigger lytic cycle activation of the phages and increased Stx...
Wed, 11/25/2020 - 10:01
Evolution of bacterial tolerance to antimicrobials precedes evolution of resistance and may result in cross-tolerance, cross-resistance, or collateral sensitivity to other antibiotics. Transient exposure of gut bacteria to glyphosate, the world’s most widely used herbicide, has been linked to the activation of the stress response and changes in susceptibility to antibiotics. In this study,...
Wed, 11/25/2020 - 10:01
Enterotoxigenic Escherichia coli (ETEC) strains are important pathogens for humans and farm animals such as pigs. Porcine ETEC strains induce diarrhea through the production of heat-labile enterotoxin (LT) and/or heat-stable enterotoxins (pSTa/STb). Although LT secretion levels differ between porcine ETEC strains, and this has been linked to virulence, it is unclear whether ST secretion levels...
Wed, 11/25/2020 - 10:01
Postweaning diarrhea (PWD) is an economically important, multifactorial disease affecting pigs within the first 2 weeks after weaning. The most common agent associated with PWD is enterotoxigenic Escherichia coli (ETEC). Currently, antibiotics are used to control PWD, and this has most likely contributed to an increased prevalence of antibiotic-resistant strains. This puts pressure on...
Wed, 11/25/2020 - 10:01
Enterotoxigenic Escherichia coli (ETEC) strains producing K88 (F4) or F18 fimbriae and enterotoxins are the predominant cause of pig postweaning diarrhea (PWD). We recently identified neutralizing epitopes of fimbriae K88 and F18, heat-labile toxin (LT), heat-stable toxins type I (STa) and type II (STb), and Shiga toxin 2e (Stx2e). In this study, we explored a novel epitope- and structure-based...
Wed, 11/25/2020 - 10:01
Enterohemorrhagic Escherichia coli (EHEC) strains, including E. coli O157:H7, cause severe illness in humans due to the production of Shiga toxin (Stx) and other virulence factors. Because Stx is coregulated with lambdoid prophage induction, its expression is especially susceptible to environmental cues. Infections with Stx-producing E. coli can be difficult to model due to the wide range of...
Wed, 11/25/2020 - 10:01
Fimbriae mediate the initial adherence of enterotoxigenic Escherichia coli (ETEC) to the piglet small intestine and play an important role in development of ETEC-driven postweaning diarrhea (PWD). PWD inflicts huge economic losses on the swine industry each year, making development of alternative treatment and prevention measures for PWD essential. Vaccine candidates that induce antifimbria...
Wed, 11/11/2020 - 10:01
Households provide a habitat for bacteria originating from humans, animals, foods, contaminated clothes, or other sources. Thus, bacteria carrying antibiotic resistance genes (ARGs) may be introduced via household members, animals, or the water supply from external habitats into private households and vice versa. Since data on antibiotic resistance (ABR) in the domestic environment are limited,...
Wed, 11/11/2020 - 10:01
This study aimed to characterize in silico enterotoxigenic Escherichia coli F4- and F18-positive isolates (n = 90) causing swine postweaning diarrhea, including pathogenic potential, phylogenetic relationship, antimicrobial and biocide resistance, prophage content, and metal tolerance rates. F4 strains belonged mostly to the O149 and O6 serogroups and ST100 and ST48 sequence types (STs). F18...
Wed, 11/11/2020 - 10:01
Microbial complexity and contamination levels in food processing plants heavily impact the final product fate and are mainly controlled by proper environmental cleaning and sanitizing. Among the emerging disinfection technologies, ozonation is considered an effective strategy to improve the ordinary cleaning and sanitizing of slaughterhouses. However, its effects on contamination levels and...
Wed, 11/11/2020 - 10:01
Cyclospora cayetanensis is a protozoan parasite that causes foodborne and waterborne diarrheal illness outbreaks worldwide. Most of these outbreaks are associated with the consumption of fresh produce. Sensitive and specific methods to detect C. cayetanensis in agricultural water are needed to identify the parasite in agricultural water used to irrigate crops that have been implicated in...
Wed, 11/11/2020 - 10:01
Oyster and seawater samples were collected from five sites in the Chesapeake Bay, MD, and three sites in the Delaware Bay, DE, from May to October 2016 and 2017. Abundances and detection frequencies for total and pathogenic Vibrio parahaemolyticus and Vibrio vulnificus were compared using the standard most-probable-number–PCR (MPN-PCR) assay and a direct-plating (DP) method on CHROMagar...
Thu, 10/29/2020 - 10:02
Bacteriophages (phages) are currently available for use by the food industry to control the foodborne pathogen Listeria monocytogenes. Although phage biocontrols are effective under specific conditions, their use can select for phage-resistant bacteria that repopulate phage-treated environments. Here, we performed short-term coevolution experiments to investigate the impact of single phages and a...
Thu, 10/29/2020 - 10:02
Zinc oxide nanoparticles (ZnO NPs) are regarded as a safe and stable antimicrobial that can inactivate bacteria by several potential working mechanisms. We aimed to incorporate ZnO NPs into packaging material to control Campylobacter in raw chicken meat. ZnO NPs were first incorporated into three-dimensional (3D) paper tubes to identify the lethal concentration against Campylobacter jejuni, which...
Thu, 10/29/2020 - 10:02
Salmonella enterica subsp. enterica serovar Abortusequi is a frequently reported pathogen causing abortion in mares. In this study, the preventive and therapeutic effects of phage PIZ SAE-01E2 against S. Abortusequi in a mouse model of abortion were investigated. Phage PIZ SAE-01E2 was stable at different temperatures (4 to 70°C) and pH values (pH 4 to 10) and could lyse the majority of the...
Fri, 10/16/2020 - 10:01
Acute hepatopancreatic necrosis disease (AHPND) is caused by PirAB toxin-producing Vibrio parahaemolyticus and has devastated the global shrimp aquaculture industry. One approach for preventing the growth of AHPND-producing Vibrio spp. is through the application of beneficial bacteria capable of inhibiting these pathogens. In this study, we focused on the inhibitory activity of Bacillus...
Fri, 10/16/2020 - 10:01
In the present study, a deep-sea bacterial strain designated Bacillus sp. strain wsm-1 was screened and found to exhibit strong antifungal activity against many plant-pathogenic fungi, and corresponding antifungal agents were thereby purified and determined by tandem mass spectrometry to be two cyclic lipopeptide homologs. These homologs, which were different from any previously reported...
Fri, 10/16/2020 - 10:01
Salmonella enterica serovar Typhimurium is a prevalent incitant of enteritis in human beings and nonhuman animals. It has been proposed that host defense responses incited by Salmonella allow the bacterium to overcome colonization resistance. Piglets (n = 24) were orally inoculated with S. enterica serovar Typhimurium DT104 or buffer alone, and the host and microbial responses were temporally...
Fri, 10/16/2020 - 10:01
Contamination of soil and water with heavy metals and metalloids is a serious environmental problem. Cadmium and arsenic are major environmental contaminants that pose a serious threat to human health. Although toxicities of cadmium and arsenic to living organisms have been extensively studied, the molecular mechanisms of cellular responses to cadmium and arsenic remain poorly understood. In this...
Fri, 10/16/2020 - 10:01
The risk of petroleum spills coupled with the potential application of chemical dispersants as a spill response strategy necessitates further understanding of the fate of oil and dispersants and their interactive effects during biodegradation. Using Arctic seawater mesocosms amended with either crude oil, Corexit 9500, or both together, we quantified the chemical losses of crude oil and Corexit...
Fri, 10/02/2020 - 10:01
Globally, gulls have been associated with carriage of high levels of Escherichia coli strains resistant to critically important antimicrobials (CIAs), a major concern, as these antimicrobials are the sole alternative or one among only a few alternatives available to treat severe life-threatening infections in humans. Previous studies of Australian silver gulls demonstrated high levels of...

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