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Applied and Environmental Microbiology

Mon, 07/01/2019 - 11:00
Detection of pathogens is crucial in food production areas. While it is well established, swabbing as a state-of-the-art sampling method offers several drawbacks with respect to yield, standardization, overall handling, and long-term monitoring. This led us to develop and evaluate a method that is easier to use at a lower cost and that should be at least as sensitive. After evaluating sundry...
Mon, 07/01/2019 - 11:00
Salmonella enterica is increasingly linked to disease outbreaks associated with consumption of low-water-activity (low-aw) foods. Persistence of the pathogen in these foods was attributed to its ability to implement desiccation resistance mechanisms. Published knowledge about methods that disrupt desiccation resistance in S. enterica is lacking. We hypothesize that strong membrane-active...
Mon, 07/01/2019 - 11:00
Salmonella spp. are among the most important foodborne pathogens and the third leading cause of human death among diarrheal diseases worldwide. Animals are the primary source of this pathogen, and animal-based foods are the main transmission route to humans. Thus, understanding the global epidemiology of Salmonella serovars is key to controlling and monitoring this bacterium. In this context,...
Mon, 07/01/2019 - 11:00
To identify and obtain the indigenous degraders metabolizing phenanthrene (PHE) and biphenyl (BP) from the complex microbial community within industrial wastewater, DNA-based stable-isotope probing (DNA-SIP) and cultivation-based methods were applied in the present study. DNA-SIP results showed that two bacterial taxa (Vogesella and Alicyclobacillus) were considered the key biodegraders...
Mon, 07/01/2019 - 11:00
Bacterial adaptation is characterized by a lag phase during which cells do not multiply or modify their physiology to cope with the constraints of their environment. Our aim was to determine a sequence of events during the lag phase of growth at low temperature and pH for three Bacillus cereus strains. The onsets of expression of two genes, one of which is essential for stress adaptation (cshA,...
Mon, 07/01/2019 - 11:00
Minicircle DNA (mcDNA), which contains only the necessary components for eukaryotic expression and is thus smaller than traditional plasmids, has been designed for application in genetic manipulation. In this study, we constructed a novel plasmid containing both the Cre recombinase under the phosphoglycerate kinase (PGK) promoter and recombinant lox66 and lox71 sites located outside the...
Mon, 07/01/2019 - 11:00
Detection of salmonellae within poultry environments is an important component of many food safety programs, but sampling approaches vary greatly and may not enable the detection of salmonellae when bacteria are present at a low prevalence or concentration. Intensive longitudinal sampling within caged sheds enabled us to undertake a longitudinal analysis of the spatial distribution of salmonellae...
Mon, 07/01/2019 - 11:00
Essential oils (EOs) have demonstrated wide-spectrum antimicrobial activities and have been actively studied for their application in foods as alternative natural preservatives. However, information regarding microbial adaptive responses and changes in virulence properties following sublethal EO exposure is still scarce. The present study investigated the effect of sublethal thymol (Thy),...
Mon, 06/17/2019 - 11:00
The effectiveness of antibiotics has been challenged by the increasing frequency of antimicrobial resistance (AMR), which has emerged as a major threat to global health. Despite its negative impact on the development of AMR, there are few effective strategies for reducing AMR in food-producing animals. Using whole-genome sequencing and comparative genomics of 36 multidrug-resistant (MDR)...
Mon, 06/17/2019 - 11:00
Methylmercury (MeHg) is a potent bioaccumulative neurotoxin that is produced by certain anaerobic bacteria and archaea. Mercury (Hg) methylation has been linked to the gene pair hgcAB, which encodes a membrane-associated corrinoid protein and a ferredoxin. Although microbial Hg methylation has been characterized in vivo, the cellular biochemistry and the specific roles of the gene products HgcA...
Mon, 06/17/2019 - 11:00
Mercury (Hg) methylation in the Florida Everglades is of great environmental concern because of its adverse effects on human and wildlife health through biomagnification in aquatic food webs. Periphyton and flocculant materials (floc) overlaying peat soil are important ecological compartments producing methylmercury (MeHg) in this ecosystem. These compartments retain higher concentrations of MeHg...
Mon, 06/17/2019 - 11:00
Enterococcus faecalis and Enterococcus faecium are human and animal gut commensals. Vancomycin-resistant enterococci (VRE) are important opportunistic pathogens with limited treatment options. Historically, the glycopeptide antibiotics vancomycin and avoparcin selected for the emergence of vancomycin resistance in human and animal isolates, respectively, resulting in global cessation of avoparcin...
Mon, 06/17/2019 - 11:00
Ceftiofur, a third-generation cephalosporin antimicrobial, was used in Canadian hatcheries for many years to prevent early mortality in chicks, leading to a high prevalence of cephalosporin resistance in Escherichia coli in chickens. Preventive use of ceftiofur in hatcheries ceased in 2014. We examined the effect of ceftiofur cessation (n = 40 flocks with ceftiofur and n = 28 flocks without...
Thu, 05/30/2019 - 11:00
An increase of Escherichia-Shigella was previously reported in acute necrotizing pancreatitis (ANP). We investigated whether Escherichia coli MG1655, an Escherichia commensal organism, increased intestinal injury and aggravated ANP in rats. ANP was induced by retrograde injection of 3.5% sodium taurocholate into the biliopancreatic duct. Using gut microbiota-depleted rats, we demonstrated that...
Thu, 05/30/2019 - 11:00
In this study, we developed a washing system capable of decontaminating fresh produce by combining the Spindle apparatus, which detaches microorganisms on sample surfaces, and a 222-nm krypton-chlorine excimer lamp (KrCl excilamp) (Sp-Ex) and investigated their decontamination effect against Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium, and Listeria monocytogenes on apple (...
Thu, 05/16/2019 - 11:01
Mahewu is a fermented cereal beverage produced in Zimbabwe. This study determined the composition and origin of mahewu microbiota. The microbiota of mahewu samples consisted of 3 to 7 dominant strains of lactobacilli and two strains of yeasts. Enterobacteriaceae were not detected. Candida glabrata was present in high cell counts from samples collected in summer but not from samples collected in...
Thu, 05/16/2019 - 11:01
Little is known about the abiotic factors contributing to the preharvest persistence of Salmonella in tomato tissues. Therefore, we investigated the effects of specific environmental conditions and contamination methods on the persistence and dissemination of Salmonella enterica subsp. enterica serotype Typhimurium (JSG626) in tomato plants. When plants were sprayed on the leaves with a JSG626-...
Thu, 05/16/2019 - 11:01
Microcin PDI (MccPDI), a class IIa microcin that is produced by Escherichia coli strains 25 and 284, is known to inhibit foodborne pathogenic enterohemorrhagic E. coli serotypes O157:H7 and O26. Here we demonstrate that MccPDI can inhibit Shigella strains and E. coli isolates that are multidrug resistant, the latter including strains known to cause urinary tract infections in people and companion...
Thu, 05/16/2019 - 11:01
Enterotoxigenic Escherichia coli (ETEC) strains that produce immunologically heterogeneous fimbriae and enterotoxins are the primary cause of neonatal diarrhea and postweaning diarrhea in young pigs. A multivalent vaccine inducing protective immunity against ideally all ETEC fimbriae and enterotoxins could be effective against diarrhea in young pigs. However, developing a vaccine to broadly...
Thu, 05/16/2019 - 11:01
Contamination of fresh produce with pathogenic Escherichia coli, including Shiga-toxigenic E. coli (STEC), represents a serious risk to human health. Colonization is governed by multiple bacterial and plant factors that can impact the probability and suitability of bacterial growth. Thus, we aimed to determine whether the growth potential of STEC for plants associated with foodborne outbreaks (...
Thu, 05/16/2019 - 11:01
Campylobacter is a major foodborne pathogen in humans and a significant cause of abortion in sheep. Although ruminants are increasingly recognized as important reservoirs for Campylobacter species, limited information is available about the molecular epidemiology and antimicrobial resistance (AMR) profiles of sheep Campylobacter. Here, we describe a two-trial study that examined Campylobacter...
Thu, 05/02/2019 - 11:02
Enterobactin (Ent)-mediated high-affinity iron acquisition is critical for Gram-negative bacteria to survive in the host. Given the bacteriostatic effect of lipocalin resulting from its potent Ent-binding ability, immune intervention directly targeting Ent is promising for iron-dependent pathogen control. Recently, an Ent conjugate vaccine was reported, but it still has several significant...
Thu, 05/02/2019 - 11:02
Untreated biological soil amendments of animal origin (BSAAO) are commonly used as biological fertilizers but can harbor foodborne pathogens like Salmonella enterica, leading to potential transfer from soils to fruits and vegetables intended for human consumption. Heat-treated poultry pellets (HTPP) can provide produce growers with a slow-release fertilizer with a minimized risk of pathogen...
Thu, 05/02/2019 - 11:02
Spore-forming bacteria are natural contaminants of food raw materials, and sporulation can occur in many environments from farm to fork. In order to characterize and to predict spore formation over time, we developed a model that describes both the kinetics of growth and the differentiation of vegetative cells into spores. The model is based on a classical growth model and enables description of...
Thu, 05/02/2019 - 11:02
Municipal wastewater includes human waste that contains both commensal and pathogenic enteric microorganisms, and this collective community microbiome can be monitored for community diseases. In a previous study, we assessed the salmonellosis disease burden using municipal wastewater from Honolulu, Hawaii, which was monitored over a 54-week period. During that time, a strain of Salmonella...
Thu, 05/02/2019 - 11:02
Western Canada produces large amounts of bitumen, a heavy, highly weathered crude oil. Douglas Channel and Hecate Strait on the coast of British Columbia are two water bodies that may be impacted by a proposed pipeline and marine shipping route for diluted bitumen (dilbit). This study investigated the potential of microbial communities from these waters to mitigate the impacts of a potential...
Thu, 05/02/2019 - 11:02
Bacteriophage lysins are compelling antimicrobial proteins whose biotechnological utility and evolvability would be aided by elevated stability. Lysin catalytic domains, which evolved as modular entities distinct from cell wall binding domains, can be classified into one of several families with highly conserved structure and function, many of which contain thousands of annotated homologous...
Thu, 04/18/2019 - 11:01
Different Bacillus species with PGPR (plant growth-promoting rhizobacterium) activity produce potent biofungicides and stimulate plant defense responses against phytopathogenic fungi. However, very little is known about how these PGPRs recognize phytopathogens and exhibit the antifungal response. Here, we report the antagonistic interaction between Bacillus subtilis and the phytopathogenic fungus...
Thu, 04/18/2019 - 11:01
Lytic bacteriophages (or phages) drive bacterial mortality by elaborating exquisite abilities to bind, breach, and destroy bacterial cell membranes and subjugate critical bacterial cell functions. These antimicrobial activities make phages ideal candidates to serve as, or provide sources of, biological control measures for bacterial pathogens. In this study, we isolated the Myoviridae phage...
Thu, 04/04/2019 - 11:00
Fe-organic matter (Fe-OM) complexes are abundant in the environment and, due to their mobility, reactivity, and bioavailability, play a significant role in the biogeochemical Fe cycle. In photic zones of aquatic environments, Fe-OM complexes can potentially be reduced and oxidized, and thus cycled, by light-dependent processes, including abiotic photoreduction of Fe(III)-OM complexes and...
Thu, 04/04/2019 - 11:00
Microbial food safety of raw or minimally processed fresh produce is a significant challenge. The current sanitation processes are effective for inactivation of bacteria in wash water but have limited efficacy (<2 log/g reduction) for inactivation of microbes on the surfaces of fresh produce. This study demonstrates a novel concept to enhance effectiveness of chlorine using a particle-based...
Thu, 04/04/2019 - 11:00
DNA is the carrier of genetic information. DNA modifications play a central role in essential physiological processes. Phosphorothioation (PT) modification involves the replacement of an oxygen atom on the DNA backbone with a sulfur atom. PT modification can cause genomic instability in Salmonella enterica under hypochlorous acid stress. This modification restores hydrogen peroxide (H2O2)...
Fri, 03/22/2019 - 11:00
Shiga toxin-producing Escherichia coli (STEC) and Campylobacter jejuni are notable health hazards associated with the consumption of raw milk. These bacteria may colonize the intestines of asymptomatic cattle and enter bulk tank milk via fecal contamination during milking. We studied the frequency of STEC O157:H7 and C. jejuni contamination in tank milk (n = 785) and the in-line milk filters of...
Fri, 03/22/2019 - 11:00
This study employed high-throughput quantitative PCR and 16S rRNA sequencing to evaluate the effect of temperature and residual antibiotics on the dynamics of antibiotic resistance genes (ARGs) and microbial communities during anaerobic digestion of swine manure. The abundances of total ARGs and 16S rRNA genes significantly decreased in all of four treatments (25°C, 37°C, and 37°C...
Fri, 03/22/2019 - 11:00
Bacteria of the genus Shigella, consisting of 4 species and >50 serotypes, cause shigellosis, a foodborne disease of significant morbidity, mortality, and economic loss worldwide. Classical Shigella identification based on selective media and serology is tedious, time-consuming, expensive, and not always accurate. A molecular diagnostic assay does not distinguish Shigella at the species level...
Wed, 03/06/2019 - 11:00
Efficient microbial conversion of lignocellulose into valuable products is often hindered by the presence of furfural, a dehydration product of pentoses in hemicellulose sugar syrups derived from woody biomass. For a cost-effective lignocellulose microbial conversion, robust biocatalysts are needed that can tolerate toxic inhibitors while maintaining optimal metabolic activities. A comprehensive...
Wed, 03/06/2019 - 11:00
We developed a multiplex PCR method based on multiple-locus variable-number tandem-repeat (VNTR) analysis (MLVA) that was designed for the rapid typing of Escherichia coli and Shigella isolates. The method amplifies seven VNTRs and does not require a sequencing capillary or fluorescent dyes. The amplification products are simply loaded on a standard agarose gel for electrophoresis, and the...
Wed, 03/06/2019 - 11:00
Atypical enteropathogenic Escherichia coli (aEPEC) strains (36 Japanese and 50 Bangladeshi) obtained from 649 poultry fecal samples were analyzed by molecular epidemiological methods. Clermont’s phylogenetic typing showed that group A was more prevalent (58%, 50/86) than B1 (31%, 27/86). Intimin type β1, which is prevalent among human diarrheal patients, was predominant in both...
Wed, 03/06/2019 - 11:00
Klebsiella pneumoniae is a leading cause of severe infections in humans and dairy cows, and these infections are rapidly becoming untreatable due to the emergence of multidrug-resistant (MDR) strains. However, little is known about the relationship between bovine and human K. pneumoniae isolates at the genome population level. Here, we investigated the genomic structures, pangenomic profiles,...
Wed, 03/06/2019 - 11:00
Aspergillus flavus is an opportunistic fungal plant and human pathogen and a producer of mycotoxins, including aflatoxin B1 (AFB1). As part of our ongoing studies to elucidate the biological functions of the A. flavus rtfA gene, we examined its role in the pathogenicity of both plant and animal model systems. rtfA encodes a putative RNA polymerase II (Pol II) transcription elongation factor...
Wed, 03/06/2019 - 11:00
In this study, we examined the change in resistance of Salmonella enterica serovar Typhimurium and Escherichia coli O157:H7 to 222-nm krypton-chlorine (KrCl) excilamp treatment as influenced by acid adaptation and identified a mechanism of resistance change. In addition, we measured changes in apple juice quality indicators, such as color, total phenols, and 2,2-diphenyl-1-picrylhydrazyl (DPPH)...
Wed, 02/20/2019 - 11:00
Campylobacter bacteria are major human enteropathogens. Campylobacter coli shows less genetic diversity than C. jejuni and clusters into three clades, of which clade 1 includes most human and farm animal isolates, while environmental C. coli isolates mainly belong to clades 2 and 3. Recently, we sequenced the whole genomes of eight C. coli clade 2 and 3 isolates cultivated from water, and here we...
Wed, 02/20/2019 - 11:00
To control the spore-forming human pathogen Bacillus cereus, we isolated and characterized a novel endolysin, LysPBC2, from a newly isolated B. cereus phage, PBC2. Compared to the narrow host range of phage PBC2, LysPBC2 showed very broad lytic activity against all Bacillus, Listeria, and Clostridium species tested. In addition to a catalytic domain and a cell wall binding domain, LysPBC2 has a...
Wed, 02/20/2019 - 11:00
Untreated biological soil amendments of animal origin (BSAAO), such as manure, are commonly used to fertilize soils for growing fruit and vegetable crops and can contain enteric bacterial foodborne pathogens. Little is known about the comparative longitudinal survival of pathogens in agricultural fields containing different types of BSAAO, and field data may be useful to determine intervals...
Wed, 02/06/2019 - 11:00
Inappropriate and disproportionate use of antibiotics is contributing immensely to the development of antibiotic resistance in bacterial species associated with food contamination. The use of natural products in combination can be a potent alternative hurdle strategy to inactivate foodborne pathogens. Here, we explored the pro-oxidant properties of essential oil linalool and vitamin C in...
Wed, 02/06/2019 - 11:00
Poultry are considered a major reservoir and source of human campylobacteriosis, but the roles of environmental reservoirs, including wild birds, have not been assessed in depth. In this study, we isolated and characterized Campylobacter jejuni from western jackdaws (n = 91, 43%), mallard ducks (n = 82, 76%), and pheasants (n = 9, 9%). Most of the western jackdaw and mallard duck C. jejuni...
Wed, 02/06/2019 - 11:00
Salmonella spp. are estimated to cause 1.2 million cases of human foodborne illness each year in the United States, and pigs can often be asymptomatically colonized with Salmonella spp. (>50% of farms). Recent reports state that 18.3% of Salmonella enterica serovar Typhimurium isolates are resistant to ≥3 antimicrobial classes, and multidrug-resistant (MDR) strains are associated with an...
Wed, 02/06/2019 - 11:00
The hypersaline Kebrit Deep brine pool in the Red Sea is characterized by high levels of toxic heavy metals. Here, we describe two structurally related mercuric reductases (MerAs) from this site which were expressed in Escherichia coli. Sequence similarities suggest that both genes are derived from proteobacteria, most likely the Betaproteobacteria or Gammaproteobacteria. We show that one of the...
Wed, 01/23/2019 - 11:00
Diet is a major determinant of intestinal microbiome composition. While studies have evaluated microbiome responses to diet variation, less is understood about how the act of feeding influences the microbiome, independent of diet type. Here, we use the clownfish Premnas biaculeatus, a species reared commonly in ornamental marine aquaculture, to test how the diversity, predicted gene content, and...
Wed, 01/23/2019 - 11:00
The characterization of native polycyclic aromatic hydrocarbon (PAH)-degrading bacteria is significant for understanding the PAH degradation process in the natural environment and developing effective remediation technologies. Most previous investigations of PAH-degrading bacteria in environmental samples employ pahAc, which encodes the α-subunit of PAH ring-hydroxylating dioxygenase, as a...

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