A Single Nucleotide Polymorphism in Increases Tolerance to Bile Salts, Acid, and Staining of Calcofluor-Binding Polysaccharides in Serovar Typhimurium E40.

The outer membrane of plays an important role in combating stress encountered in the environment and hosts. The transport and insertion of lipopolysaccharides (LPS) into the outer membrane involves lipopolysaccharide transport proteins (LptA-F) and mutations in the genes encoding for these proteins are often lethal or result in the transport of atypical LPS that can alter stress tolerance in bacteria. During studies of heterogeneity in bile salts tolerance, serovar Typhimurium E40 was segregated into bile salts tolerant and sensitive cells by screening for growth in TSB with 10% bile salts.

Chronological set of E. coli O157:H7 bovine strains establishes a role for repeat sequences and mobile genetic elements in genome diversification.

Background: Enterohemorrhagic Escherichia coli O157:H7 (EHEC) is a significant foodborne pathogen that resides asymptomatically within cattle and other ruminants. The EHEC genome harbors an extensive collection of mobile genetic elements (MGE), including multiple prophage, prophage-like elements, plasmids, and insertion sequence (IS) elements.

Results: A chronological collection of EHEC strains (FRIK804, FRIK1275, and FRIK1625) isolated from a Wisconsin dairy farm (farm X) comprised a closely related clade genetically differentiated by structural alterations to the chromosome.

Genome Sequences of 14 Escherichia coli O157:H7 Strains Isolated before and during the Time Frame of the 2018 Multistate Outbreak Associated with Romaine Lettuce.

Several outbreaks of O157:H7 associated with contaminated leafy green vegetables have been documented. Here, we report the draft genome sequences of 14 strains isolated from human patients in the state of Wisconsin during a multistate outbreak in early 2018 that was linked to consumption of romaine lettuce.

Genome Sequence of the Extremely Acidophilic Fungus Acidomyces richmondensis FRIK2901.

Acidomyces richmondensis is an extremophilic fungal species found in warm, acidic, and metal-rich environments. To improve upon the existing reference genome, we used PacBio and Illumina sequencing to assemble a highly contiguous 29.3-Mb genome of A.

Phosphate and carbohydrate facilitate the formation of filamentous Salmonella enterica during osmotic stress.

Salmonella enterica is a human pathogen that can produce filamentous cells in response to environmental stress. The molecular mediators and biosynthetic pathways that contribute to the formation of filamentous cells (>10 µm in length) during osmotic stress are mostly unknown. The comparison of filamentous and non-filamentous cells in this study was aided by the use of a filtration step to separate cell types.

Evaluating the efficacy of beef slaughter line interventions by quantifying the six major non-O157 Shiga toxin producing Escherichia coli serogroups using real-time multiplex PCR.

Six major Shiga toxin producing Escherichia coli (STEC) serogroups: O26, O103, O145, O111, O121, and O45 have been declared as adulterants in federally inspected raw beef in the USA effective June 4th, 2012 in addition to the routinely tested STEC O157: H7. This study tests a real-time multiplex PCR assay and pooling of the samples to optimize the detection and quantification (prevalence and contamination) of six major non-O157 STEC, regardless of possessing Shiga toxins. To demonstrate the practicality, one large-scale slaughter plant (Plant LS) and one small-scale slaughter plant (Plant SS) located in the Mid-Western USA were sampled, in 2011, before the establishment of 2013 USDA laboratory protocols.

Gene markers of generic Escherichia coli associated with colonization and persistence of Escherichia coli O157 in cattle.

Enterohemorrhagic Escherichia coli (EHEC) O157 are important foodborne pathogens whose major reservoir are asymptomatic cattle. There is evidence suggesting that nonpathogenic E. coli and bacteriophages in the gastro-intestinal tract can influence the pathogenicity of EHEC O157.

RpoS impacts the lag phase of Salmonella enterica during osmotic stress.

Salmonella enterica can survive harsh environmental conditions, including hyperosmotic stress. It is well established that the alternative sigma factor, σ(s) (RpoS), is required for maximal survival of enteric pathogens, including S. enterica.

Response of Medicago truncatula seedlings to colonization by Salmonella enterica and Escherichia coli O157:H7.

Disease outbreaks due to the consumption of legume seedlings contaminated with human enteric bacterial pathogens like Escherichia coli O157:H7 and Salmonella enterica are reported every year. Besides contaminations occurring during food processing, pathogens present on the surface or interior of plant tissues are also responsible for such outbreaks. In the present study, surface and internal colonization of Medicago truncatula, a close relative of alfalfa, by Salmonella enterica and Escherichia coli O157:H7 were observed even with inoculum levels as low as two bacteria per plant.

Phylogenetic characterization of Escherichia coli O157 : H7 based on IS629 distribution and Shiga toxin genotype.

Shiga toxin (stx)-producing Escherichia coli O157 : H7 is a prominent food-borne pathogen. Symptoms in human infections range from asymptomatic to haemorrhagic colitis and haemolytic uraemic syndrome, and there is a need for methods that yield information that can be used to better predict clinical and epidemiological outcomes. IS629 is an insertion sequence notable for its prevalence and variable distribution in the chromosome of E.

Evolution of the Stx2-encoding prophage in persistent bovine Escherichia coli O157:H7 strains.

Escherichia coli O157:H7 is a human pathogen that resides asymptomatically in its bovine host. The level of Shiga toxin (Stx) produced is variable in bovine-derived strains in contrast to human isolates that mostly produce high levels of Stx. To understand the genetic basis for varied Stx production, chronological collections of bovine isolates from Wisconsin dairy farms, R and X, were analyzed for multilocus prophage polymorphisms, stx(2) subtypes, and the levels of stx(2) transcript and toxin.

Prevalent and persistent Escherichia coli O157:H7 strains on farms are selected by bovine passage.

Escherichia coli O157:H7 is a human pathogen capable of causing hemorrhagic colitis and in some cases hemolytic uremic syndrome. Cattle are an asymptomatic carrier and a major reservoir of this pathogen that can be transmitted by contaminated foods like beef products and vegetables. To further understand persistence in cattle and on farms, a total of 1716 samples over a two-year period were collected from a Wisconsin dairy farm (Farm R) and 91 were positive for the presence of E.

Differences in colonization and shedding patterns after oral challenge of cattle with three Escherichia coli O157:H7 strains.

Experimental oral challenge studies with three different genotypes of Escherichia coli O157:H7 were conducted in cattle to determine the genotype-specific variability in shedding frequencies and concentrations and the frequency and extent of contamination of the environment. The results indicated that the E. coli O157:H7 genotype and ecological origin maybe important factors for the occurrence and concentration in the cattle host.

Osmotic and desiccation tolerance in Escherichia coli O157:H7 requires rpoS (σ(38)).

The contribution of RecA, Dps, and RpoS to survival of Escherichia coli O157:H7 during desiccation and osmotic stress was determined in Luria-Bertani broth with 12 % NaCl (LB-12) at 30 and 37 °C, on filter disks at 23 and 30 °C, and in sterile bovine feces at 30 °C. RecA did not significantly contribute to survival in any condition or temperature. The contribution of Dps to survival was only significant in LB-12 at 37 °C.

Characterization of osmotically induced filaments of Salmonella enterica.

Salmonella enterica forms aseptate filaments with multiple nucleoids when cultured in hyperosmotic conditions. These osmotic-induced filaments are viable and form single colonies on agar plates even though they contain multiple genomes and have the potential to divide into multiple daughter cells. Introducing filaments that are formed during osmotic stress into culture conditions without additional humectants results in the formation of septa and their division into individual cells, which could present challenges to retrospective analyses of infectious dose and risk assessments.

Validation of pepperoni process for control of Shiga toxin-producing Escherichia coli.

The objective of this study was to compare the survival of non-O157 Shiga toxin-producing Escherichia coli (STEC) with E. coli O157:H7 during pepperoni production. Pepperoni batter was inoculated with 7 log CFU/g of a seven-strain STEC mixture, including strains of serotypes O26, O45, O103, O111, O121, O145, and O157.

Rapid and reliable detection of Shiga toxin-producing Escherichia coli by real-time multiplex PCR.

Escherichia coli O26, O45, O103, O111, O121, O145, and O157 are the predominant Shiga toxin-producing E. coli (STEC) serogroups implicated in outbreaks of human foodborne illness worldwide. The increasing prevalence of these pathogens has important public health implications.

Survival and virulence of Salmonella enterica serovar enteritidis filaments induced by reduced water activity.

Salmonella enterica serovar Enteritidis strain E40 filaments were developed under conditions of a reduced water activity (a(w)) of 0.95 in tryptic soy broth (TSB) or tryptic soy agar (TSA) supplemented with 8% or 7% NaCl, respectively. Filament formation was accompanied by an increase of biomass without an increase in CFU and was affected by incubation temperature and the physical milieu.

A high-throughput open-array qPCR gene panel to identify, virulotype, and subtype O157 and non-O157 enterohemorrhagic Escherichia coli.

Enterohemorrhagic Escherichia coli (EHEC), including O157 and non-O157 serotypes are significant foodborne pathogens that require sensitive and discriminatory methods for detection and characterization. There are numerous PCR-based methods for the detection of EHEC virulence factors, but the time and cost involved with large-scale screening efforts and population level analyses have limited the size and scope of studies. Recent technological advancements have combined the high-throughput performance of the microarray with the specificity and sensitivity of real-time qPCR to make large-scale screening efforts both time- and cost-effective.

Reduction of Escherichia coli O157:H7 shedding in cattle by addition of chitosan microparticles to feed.

Enterohemorrhagic Escherichia coli O157:H7 (EHEC) is a significant human pathogen that resides in healthy cattle. It is thought that a reduction in the prevalence and numbers of EHEC in cattle will reduce the load of EHEC entering the food chain. To this end, an intervention strategy involving the addition of chitosan microparticles (CM) to feed in order to reduce the carriage of this pathogen in cattle was evaluated.

Molybdate treatment and sulfate starvation decrease ATP and DNA levels in Ferroplasma acidarmanu.

Sulfate is a primary source of sulfur for most microbes and in some prokaryotes it is used an electron acceptor. The acidophile Ferroplasma acidarmanus (strain fer1) requires a minimum of 150 mM of a sulfate-containing salt for growth. Sulfate is assimilated by F.

Acid stress damage of DNA is prevented by Dps binding in Escherichia coli O157:H7.

Background: Acid tolerance in Escherichia coli O157:H7 contributes to persistence in its bovine host and is thought to promote passage through the gastric barrier of humans. Dps (DNA-binding protein in starved cells) mutants of E. coli have reduced acid tolerance when compared to the parent strain although the role of Dps in acid tolerance is unclear.

Production of methanethiol and volatile sulfur compounds by the archaeon "Ferroplasma acidarmanus".

Acidophiles are typically isolated from sulfate-rich ecological niches yet the role of sulfur metabolism in their growth and survival is poorly defined. Studies of heterotrophically grown "Ferroplasma acidarmanus" showed that its growth requires a minimum of 100 mM of a sulfate-containing salt. Headspace gas analyses by GC/MS determined that the volatile sulfur compound emitted by active "F.

H-NS controls metabolism and stress tolerance in Escherichia coli O157:H7 that influence mouse passage.

Background: H-NS is a DNA-binding protein with central roles in gene regulation and nucleoid structuring in Escherichia coli. There are over 60 genes that are influenced by H-NS many of which are involved in metabolism. To determine the significance of H-NS-regulated genes in metabolism and stress tolerance, an hns mutant of E.

Enhancement of acid tolerance in Zymomonas mobilis by a proton-buffering peptide.

A portion of the cbpA gene from Escherichia coli K-12 encoding a 24 amino acid proton-buffering peptide (Pbp) was cloned via the shuttle vector pJB99 into E. coli JM105 and subsequently into Zymomonas mobilis CP4. Expression of Pbp was confirmed in both JM105 and CP4 by HPLC.