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https://www.readbyqxmd.com/read/29346603/homologous-stress-adaptation-antibiotic-resistance-and-biofilm-forming-ability-of-salmonella-enterica-serovar-heidelberg-atcc8326-on-different-food-contact-surfaces-following-exposure-to-sublethal-chlorine-concentrations
#1
Tomi Obe, Rama Nannapaneni, Chander Shekhar Sharma, Aaron Kiess
Salmonella enterica serovar Heidelberg (American Type Culture Collection; ATCC 8326) was examined for the ability to adapt to the homologous stress of chlorine through exposure to increasing chlorine concentrations (25 ppm daily increments) in tryptic soy broth (TSB). The tested strain exhibited an acquired tolerance to chlorine in TSB with the tolerant cells growing in concentrations up to 400 ppm. In addition, the chlorine stressed cells displayed rugose morphology on tryptic soy agar (TSA) plates at 37°C...
January 13, 2018: Poultry Science
https://www.readbyqxmd.com/read/29321057/influenza-a-virus-infection-impacts-systemic-microbiota-dynamics-and-causes-quantitative-enteric-dysbiosis
#2
Soner Yildiz, Béryl Mazel-Sanchez, Matheswaran Kandasamy, Balaji Manicassamy, Mirco Schmolke
BACKGROUND: Microbiota integrity is essential for a growing number of physiological processes. Consequently, disruption of microbiota homeostasis correlates with a variety of pathological states. Importantly, commensal microbiota provide a shield against invading bacterial pathogens, probably by direct competition. The impact of viral infections on host microbiota composition and dynamics is poorly understood. Influenza A viruses (IAV) are common respiratory pathogens causing acute infections...
January 10, 2018: Microbiome
https://www.readbyqxmd.com/read/29306008/the-mals-5-utr-weakens-the-ability-of-salmonella-enterica-serovar-typhi-to-survive-in-macrophages-by-increasing-intracellular-atp-levels
#3
Fang Dong, Lin Xia, Renfei Lu, Xin Zhao, Yiquan Zhang, Ying Zhang, Xinxiang Huang
Bacterial non-coding RNAs (ncRNAs), as important regulatory factors, are involved in many cellular processes, including virulence and protection against environmental stress. The 5' untranslated region (UTR) of malS (named malS-5'UTR), a regulatory ncRNA, increases the invasive capacity and influences histidine biosynthesis in Salmonella enterica serovar Typhi (S. Typhi). In this study, we found that overexpression of the malS-5'UTR decreased S. Typhi survival within macrophages. A microarray analysis of a strain overexpressing the malS-5'UTR revealed a significant increase in the mRNA levels of the atp operon...
January 3, 2018: Microbial Pathogenesis
https://www.readbyqxmd.com/read/29305504/an-igaa-umob-family-protein-from-serratia-marcescens-regulates-motility-capsular-polysaccharide-and-secondary-metabolite-production
#4
Nicholas A Stella, Kimberly M Brothers, Jake D Callaghan, Angelina M Passerini, Cihad Sigindere, Preston J Hill, Xinyu Liu, Daniel J Wozniak, Robert M Q Shanks
Secondary metabolites are an important source of pharmaceuticals and key modulators of microbe-microbe interactions. The bacterium Serratia marcescens is part of the Enterobacteriaceae family of eubacteria and produces a number of biologically active secondary metabolites. In this study, we screened for novel regulators of secondary metabolites synthesized by a clinical isolate of S. marcescens and found mutations in a gene for an uncharacterized UmoB/IgaA family member here named gumB Mutation of gumB conferred a severe loss of secondary metabolites prodigiosin and serratamolide...
January 5, 2018: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/29258895/estimation-of-structure-and-stability-of-mure-ligase-from-salmonella-enterica-serovar-typhi
#5
Rohit Bansal, Md Anzarul Haque, Prakarsh Yadav, Deepali Gupta, Abdul S Ethayathulla, Md Imtaiyaz Hassan, Punit Kaur
MurE ligase catalyzes the assembly of peptide moiety, an essential component of bacterial cell wall. We have explored the conformational stability and unfolding equilibrium behaviour of the protein MurE ligase by determining the conformational free energy, entropy and enthalpy parameters under stress conditions. MurE from Salmonella enterica Serovar Typhi was cloned, expressed and purified. Conformational changes associated with increasing concentration of GdmCl- and urea-induced denaturation of MurE were monitored using Circular Dichroism (CD) and fluorescence spectroscopies...
December 16, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/29232632/inactivation-of-escherichia-coli-o157-h7-and-salmonella-deposited-on-gloves-in-a-liquid-state-and-subjected-to-drying-conditions
#6
Marilyn C Erickson, Jye-Yin Liao, Cathy C Webb, Mussie Y Habteselassie, Jennifer L Cannon
Gloves are worn by workers harvesting ready-to-eat produce as a deterrent for contaminating the produce with enteric pathogens that may reside on their hands. As fields are not sterile environments, the probability for gloves to become contaminated still exists and therefore it is critical to understand the conditions that affect the survival of pathogens on gloves. Both Escherichia coli O157:H7 and Salmonella deposited on glove surfaces in a liquid state survived longer when the pathogen had been suspended in lettuce sap than when suspended in water...
November 29, 2017: International Journal of Food Microbiology
https://www.readbyqxmd.com/read/29232043/an-erwinia-amylovora-yjek-mutant-exhibits-reduced-virulence-increased-chemical-sensitivity-and-numerous-environmentally-dependent-proteomic-alterations
#7
Sara Klee, Islam Mostafa, Sixue Chen, Craig Dufresne, Brian L Lehman, Judith P Sinn, Kari A Peter, Timothy W McNellis
The gram-negative bacterium Erwinia amylovora causes fire blight, an economically-important disease of apples and pears. Elongation Factor P (EF-P) is a highly conserved protein that stimulates the formation of the first peptide bond of certain proteins and facilitates translation of certain proteins, including those with polyproline motifs. YjeK and YjeA are two enzymes involved in the essential post-translational β-lysylation of EF-P at a conserved lysine residue, K34. EF-P, YjeA, and YjeK have been shown to be essential for full virulence of Escherichia coli, Salmonella species, and Agrobacterium tumefaciens, with efp, yjeA, and yjeK mutants having highly similar phenotypes...
December 12, 2017: Molecular Plant Pathology
https://www.readbyqxmd.com/read/29214489/direct-interaction-between-the-transcription-factors-cadc-and-ompr-involved-in-the-acid-stress-response-of-salmonella-enterica
#8
Yong Heon Lee, Ji Hye Kim
In Salmonella enterica serovar Typhimurium, the acid-sensing regulator CadC activates transcription of the cadBA operon which contributes to the acid tolerance response. The DNA-binding response regulator OmpR in two-component regulatory system with EnvZ binds to its own promoter for autoinduction. We previously reported that CadC exerts a negative influence on ompR transcription during acid adaptation. However, its underlying mechanisms remain to be elucidated. Here we show that the level of OmpR protein is gradually reduced by a gradual increase in the CadC level using an arabinose-inducible expression system, indicating there exists a negative correlation between the expression levels of two transcription factors...
December 2017: Journal of Microbiology / the Microbiological Society of Korea
https://www.readbyqxmd.com/read/29196295/quasi-metagenomics-and-realtime-sequencing-aided-detection-and-subtyping-of-salmonella-enterica-from-food-samples
#9
Ji-Yeon Hyeon, Shaoting Li, David A Mann, Shaokang Zhang, Zhen Li, Yi Chen, Xiangyu Deng
Metagenomics analysis of food samples promises isolation-independent detection and subtyping of foodborne bacterial pathogens in a single workflow. Selective concentration of Salmonella genomic DNA through immunomagnetic separation (IMS) and multiple displacement amplification (MDA) were shown to shorten culture enrichment of Salmonella-spiked raw chicken breast samples by over 12 hours while permitting serotyping and high-fidelity single nucleotide polymorphisms (SNP) typing of the pathogen using short shotgun sequencing reads...
December 1, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/29195981/stress-adaptation-has-a-minor-impact-on-the-effectivity-of-non-thermal-atmospheric-plasma-ntap-against-salmonella-spp
#10
Tamara Calvo, Avelino Alvarez-Ordóñez, Miguel Prieto, Ana Bernardo, Mercedes López
This study was aimed at studying the influence of gas composition (air and nitrogen) at different flow rates (5, 10 and 15Lm-1) and stress adaptation (growth under a wide range of temperatures [10-45°C] and acid conditions [up to pH4.5, using different organic acids] or short-term exposure to acid, cold or heat stress shocks) on the inactivation by Non-Thermal Atmospheric Plasma (NTAP) of S. Typhimurium CECT 443 and S. Enteritidis CECT 4300. Results obtained evidence that microbial inactivation was significantly higher when air was used for NTAP treatments...
December 2017: Food Research International
https://www.readbyqxmd.com/read/29183977/osmosensing-by-the-bacterial-phoq-phop-two-component-system
#11
Jing Yuan, Fan Jin, Timo Glatter, Victor Sourjik
The PhoQ/PhoP two-component system plays an essential role in the response of enterobacteria to the environment of their mammalian hosts. It is known to sense several stimuli that are potentially associated with the host, including extracellular magnesium limitation, low pH, and the presence of cationic antimicrobial peptides. Here, we show that the PhoQ/PhoP two-component systems of Escherichia coli and Salmonella can also perceive an osmotic upshift, another key stimulus to which bacteria become exposed within the host...
November 28, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29172985/impact-of-desiccation-and-heat-exposure-stress-on-salmonella-tolerance-to-acidic-conditions
#12
Kurt E Richardson, Nelson A Cox, Douglas E Cosby, Mark E Berrang
In a recent study, the pH of commonly used Salmonella pre-enrichment media became acidic (pH 4.0 to 5.0) when feed or feed ingredients were incubated for 24 h. Acidic conditions have been reported to injure or kill Salmonella. In this study, cultures of four known feed isolates (S. montevideo, S. senftenberg, S. tennessee, and S. schwarzengrund) and four important processing plant isolates (S. typhimurium, S. enteritidis, S. infantis, and S. heidelberg) were grown on meat and bone meal and later subjected to desiccation and heat exposure to stress the microorganism...
November 27, 2017: Journal of Environmental Science and Health. Part. B, Pesticides, Food Contaminants, and Agricultural Wastes
https://www.readbyqxmd.com/read/29157080/secretory-autophagy-holds-the-key-to-lysozyme-secretion-during-bacterial-infection-of-the-intestine
#13
Elizabeth Delorme-Axford, Daniel J Klionsky
In 2013, Dr. Lora Hooper and colleagues described the induction of antibacterial macroautophagy/autophagy in intestinal epithelial cells as a cytoprotective host defense mechanism against invading Salmonella enterica serovar Typhimurium (S. Typhimurium). Canonical autophagy functions in a primarily degradative capacity to safeguard cells and ensure survival during stress conditions, including pathogen infection. In contrast, secretory autophagy has emerged as an alternative nondegradative mechanism for cellular trafficking and unconventional protein secretion...
November 20, 2017: Autophagy
https://www.readbyqxmd.com/read/29150501/glna-truncation-in-salmonella-enterica-results-in-a-small-colony-variant-phenotype-attenuated-host-cell-entry-and-reduced-expression-of-flagellin-and-spi-1-associated-effector-genes
#14
Philipp Aurass, Juliane Düvel, Susanne Karste, Ulrich Nübel, Wolfgang Rabsch, Antje Flieger
Many pathogenic bacteria use sophisticated survival strategies to overcome harsh environmental conditions. One is the formation of slow-growing subpopulations termed small colony variants (SCVs). Here we characterize an SCV, which spontaneously emerged from an axenic Salmonella enterica serovar Typhimurium water culture. We found that the SCV harbors a frameshift mutation in the glutamine synthetase gene glnA leading to a ∼90% truncation of the corresponding protein. Glutamine synthetase, a central enzyme in nitrogen assimilation, converts glutamate and ammonia to glutamine...
November 17, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/29146500/motility-biofilm-formation-apoptotic-effect-and-virulence-gene-expression-of-atypical-salmonella-typhimurium-outside-and-inside-caco-2-cells
#15
Ibtissem Chakroun, Abdelkarim Mahdhi, Patricia Morcillo, Hector Cordero, Alberto Cuesta, Amina Bakhrouf, Kacem Mahdouani, M Ángeles Esteban
Disease outbreaks related to waterborne pathogen contamination throughout the world as well as challenges that lie ahead for addressing persistent infection are of renewed interest. In this research, we studied the effects of prolonged exposure of Salmonella enterica serovar Typhimurium to the cues encountered in the extracellular environment particularly in seawater microcosm on bacterial virulence and subsequent infection in Caco-2 cells. Our data show a significant difference in biofilm formation, swimming and swarming motilities between normal and stressed cells of S...
November 13, 2017: Microbial Pathogenesis
https://www.readbyqxmd.com/read/29142277/genetic-metabolomic-and-transcriptomic-analyses-of-the-de-novo-l-cysteine-biosynthetic-pathway-in-the-enteric-protozoan-parasite-entamoeba-histolytica
#16
Ghulam Jeelani, Dan Sato, Tomoyoshi Soga, Tomoyoshi Nozaki
The de novo L-cysteine biosynthetic pathway is critical for the growth, antioxidative stress defenses, and pathogenesis of bacterial and protozoan pathogens, such as Salmonella typhimurium and Entamoeba histolytica. This pathway involves two key enzymes, serine acetyltransferase (SAT) and cysteine synthase (CS), which are absent in mammals and therefore represent rational drug targets. The human parasite E. histolytica possesses three SAT and CS isozymes; however, the specific roles of individual isoforms and significance of such apparent redundancy remains unclear...
November 15, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29140975/natural-variation-of-a-sensor-kinase-controlling-a-conserved-stress-response-pathway-in-escherichia-coli
#17
Manuela Roggiani, Srujana S Yadavalli, Mark Goulian
Previous studies have shown that exponentially growing Escherichia coli can detect mild acidity (~pH 5.5) and, in response, synthesize enzymes that protect against severe acid shock. This adaptation is controlled by the EvgS/EvgA phosphorelay, a signal transduction system present in virtually every E. coli isolate whose genome has been sequenced. Here we show that, despite this high level of conservation, the EvgS/EvgA system displays a surprising natural variation in pH-sensing capacity, with some strains entirely non-responsive to low pH stimulus...
November 15, 2017: PLoS Genetics
https://www.readbyqxmd.com/read/29138484/non-canonical-activation-of-ompr-drives-acid-and-osmotic-stress-responses-in-single-bacterial-cells
#18
Smarajit Chakraborty, Ricksen S Winardhi, Leslie K Morgan, Jie Yan, Linda J Kenney
Unlike eukaryotes, bacteria undergo large changes in osmolality and cytoplasmic pH. It has been described that during acid stress, bacteria internal pH promptly acidifies, followed by recovery. Here, using pH imaging in single living cells, we show that following acid stress, bacteria maintain an acidic cytoplasm and the osmotic stress transcription factor OmpR is required for acidification. The activation of this response is non-canonical, involving a regulatory mechanism requiring the OmpR cognate kinase EnvZ, but not OmpR phosphorylation...
November 14, 2017: Nature Communications
https://www.readbyqxmd.com/read/29138083/adaptations-in-the-physiological-heterogeneity-and-viability-of-shigella-dysenteriae-shigella-flexneri-and-salmonella-typhimurium-after-exposure-to-simulated-gastric-acid-fluid
#19
Atheesha Singh, Tobias George Barnard
Stomach acidity is an important barrier of the human body to protect itself from microbial pathogens entering the small intestine and causing infection. This study examined the survival adaptations of non-acid adapted diarrheal Shigella and Salmonella strains in an environment mimicking the human stomach. The bacterial responses to the challenge of acidic simulated gastric fluid were studied using flow cytometry physiological heterogeneity, membrane integrity and survival (culturability) respectively. Flow cytometry showed that bacterial cells, when exposed to gastric fluid, transformed distinctly, into physiologically heterogeneous sub-populations: intact, stressed and damaged cells, when stained with propidium iodide and thiazole orange...
November 11, 2017: Microbial Pathogenesis
https://www.readbyqxmd.com/read/29118452/magnesium-homeostasis-protects-salmonella-against-nitrooxidative-stress
#20
Travis J Bourret, Lin Liu, Jeff A Shaw, Maroof Husain, Andrés Vázquez-Torres
The PhoPQ two-component regulatory system coordinates the response of Salmonella enterica serovar Typhimurium to diverse environmental challenges encountered during infection of hosts, including changes in Mg(2+) concentrations, pH, and antimicrobial peptides. Moreover, PhoPQ-dependent regulation of gene expression promotes intracellular survival of Salmonella in macrophages, and contributes to the resistance of this pathogen to reactive nitrogen species (RNS) generated from the nitric oxide produced by the inducible nitric oxide (NO) synthase of macrophages...
November 8, 2017: Scientific Reports
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