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Physiological and transcriptional response of Lactobacillus casei ATCC 334 to acid stress

ABSTRACT: This study investigated features of the acid tolerance response (ATR) in Lactobacillus casei ATCC 334. To optimize ATR induction, cells were acid adapted for 10 or 20 min at different pH values (range, 3.0 to 5.0) and then acid challenged at pH 2.0. Adaptation over a broad range of pHs improved acid tolerance, but the highest survival was noted in cells acid adapted for 10 or 20 min at pH 4.5. Analysis of cytoplasmic membrane fatty acids (CMFAs) in acid-adapted cells showed that they had significantly (P < 0.05) higher total percentages of saturated and cyclopropane fatty acids than did control cells. Specifically, large increases in the percentages of C(14:0), C(16:1n(9)), C(16:0), and C(19:0(11c)) were noted in the CMFAs of acid-adapted and acid-adapted, acid-challenged cells, while C(18:1n(9)) and C(18:1n(11)) showed the greatest decrease. Comparison of the transcriptome from control cells (grown at pH 6.0) against that from cells acid adapted for 20 min at pH 4.5 indicated that acid adaption invoked a stringent-type response that was accompanied by other functions which likely helped these cells resist acid damage, including malolactic fermentation and intracellular accumulation of His. Validation of microarray data was provided by experiments that showed that L. casei survival at pH 2.5 was improved at least 100-fold by chemical induction of the stringent response or by the addition of 30 mM malate or 30 mM histidine to the acid challenge medium. To our knowledge, this is the first report that intracellular histidine accumulation may be involved in bacterial acid resistance.

ORGANISM(S): Lactobacillus helveticus Lacticaseibacillus paracasei ATCC 334

PROVIDER: GSE22318 | GEO | 2010/06/16

SECONDARY ACCESSION(S): PRJNA127371

REPOSITORIES: GEO

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Physiological and transcriptional response of Lactobacillus casei ATCC 334 to acid stress

Project description:This study investigated features of the acid tolerance response (ATR) in Lactobacillus casei ATCC 334. To optimize ATR induction, cells were acid adapted for 10 or 20 min at different pH values (range, 3.0 to 5.0) and then acid challenged at pH 2.0. Adaptation over a broad range of pHs improved acid tolerance, but the highest survival was noted in cells acid adapted for 10 or 20 min at pH 4.5. Analysis of cytoplasmic membrane fatty acids (CMFAs) in acid-adapted cells showed that they had significantly (P < 0.05) higher total percentages of saturated and cyclopropane fatty acids than did control cells. Specifically, large increases in the percentages of C(14:0), C(16:1n(9)), C(16:0), and C(19:0(11c)) were noted in the CMFAs of acid-adapted and acid-adapted, acid-challenged cells, while C(18:1n(9)) and C(18:1n(11)) showed the greatest decrease. Comparison of the transcriptome from control cells (grown at pH 6.0) against that from cells acid adapted for 20 min at pH 4.5 indicated that acid adaption invoked a stringent-type response that was accompanied by other functions which likely helped these cells resist acid damage, including malolactic fermentation and intracellular accumulation of His. Validation of microarray data was provided by experiments that showed that L. casei survival at pH 2.5 was improved at least 100-fold by chemical induction of the stringent response or by the addition of 30 mM malate or 30 mM histidine to the acid challenge medium. To our knowledge, this is the first report that intracellular histidine accumulation may be involved in bacterial acid resistance. This study includes 5 samples that were analyzed (this includes a control). Four replicates were done on the full experiment. The control was cells that received no acid treatment prior to RNA isolation

2010-06-15 | E-GEOD-22318 | biostudies-arrayexpress

Identification of HP0244 regulon at different pH conditions

Project description:Transcriptional profiling of Helicobacter pylori comparing 26695 wild-type strain and a HP0244-deficient mutant 26695/∆HP0244::km treated at three different pH conditions (pH 7.4, pH 4.5 without urea, or pH 2.5 with 30 mM urea) for 30 min to define the HP0244 acid-responsive regulon Keywords: Genetic modification and stress response

2009-09-14 | GSE12900 | GEO

Dissecting acid stress response in Rhizobium tropici CIAT 899

Project description:Rhizobium tropici CIAT899 is a nodule-forming α-proteobacterium displaying intrinsic resistance to several abiotic stress conditions such as low soil pH and high temperatures, which are common in tropical environments. It is a good competitor for Phaseolus vulgaris (common bean) nodule occupancy at low pH values, however little is known about the genetic or physiological basis of acid tolerance about gene expression under acidic conditions. To identify genes responding to pH stress we studied the transcriptomes of cells grown under different pH conditions. RNA was extracted from cells grown for several generations in minimal medium at 6.8 or 4.5 (adapted cells). In addition, we acid-shocked cells pre-grown at pH 6.8 for 45 minutes at pH 4.5. Transcriptomes were determined by RNA-Seq. From a total of 6289 protein-coding genes, 383 were found to be differentially expressed under acidic conditions versus control, among which 351 were induced and 32 repressed; only 11 genes were induced upon acid shock. The acid stress response of R. tropici CIAT899 is versatile: we found genes encoding response regulators and membrane transporters, but also enzymes involved in amino acid and carbohydrate metabolism and proton extrusion. Our findings enhance our understanding of the core genes that are important during the acid stress response in R. tropici.

2018-05-17 | GSE108074 | GEO

Transcription profiling of E. coli K-12 and O157:H7 during exposure to acetic, lactic, and hydrochloric acid at pH 5.5

Project description:The foodborne pathogen Escherichia coli O157:H7 is commonly exposed to organic acid in processed and preserved foods, allowing adaptation and the development of tolerance to pH levels otherwise lethal. Since little is known about the molecular basis of adaptation of E. coli to organic acids, we studied K-12 MG1655 and O157:H7 Sakai during exposure to acetic-, lactic-, and hydrochloric acid at pH 5.5. The conditions required to maximimally induce the ATR of the pathotypes to all acidulants was experimentally determined. This involved incubation at pH 5.5 for 3 h (K-12) and for 2 h (O157:H7), and generated acid adapted cultures more resistant to acid challenge at pH 3.5 than bacteria that had been grown at neutral pH prior to acid-shock. To determine the transcriptomic response of K-12 and O157:H7 to each of the three acids, RNA was extracted from samples of cultures at the time of incubation corresponding to maximal induction of the ATR and from the corresponding overnight culture to serve as a control. The Affy package of the Bioconductor software was used to process raw CEL files using the robust multiarray average algorithm (RMA) for normalization, background correction, and expression value calculation. Expression levels obtained from four independent biological replicates of every condition were compared using the Limma package of the Bioconductor software. Elements with expression levels ? twofold higher or lower than the reference at a statistical significance (P-value adjustment with Benjamini and Hochberg with an adjusted P value ? 0.01, Average Expression (A value) ? 2, Log-odds (B value) ? 0) were selected. This is the first transcriptomic study to demonstrate and characterise the stationary phase acidulant and pathotype specific ATR of E. coli. A core set of genes were also found to be universally expressed by both pathotypes regardless of acidulant type.

2010-10-08 | E-TABM-912 | biostudies-arrayexpress

Identification of HP0244 regulon at different pH conditions

Project description:Transcriptional profiling of Helicobacter pylori comparing 26695 wild-type strain and a HP0244-deficient mutant 26695/âHP0244::km treated at three different pH conditions (pH 7.4, pH 4.5 without urea, or pH 2.5 with 30 mM urea) for 30 min to define the HP0244 acid-responsive regulon Keywords: Genetic modification and stress response Wild type vs HP0244-deficient mutant at three different pH conditions (pH7.4, pH4.5 without urea, and pH2.5 with 30 mM urea). Three biological replicates for each pH condition: 3 wild type and 3 mutant, independently grown, pH treated, and harvested.

2010-05-05 | E-GEOD-12900 | biostudies-arrayexpress

Salmonella Typhimurium: Heat-shocked cells vs. control cells and acid-shocked cells vs. control cells

Project description:We investigated if the transcriptional response of S. Typhimurium to temperature and acid variations was hysteretic and showed memory, i.e., if the transcriptional regulation caused by environmental stimuli remained after the stimuli ceased. The transcriptional activity of non-replicating stationary-phase cells of Salmonella Typhimurium caused by the exposure to 45°C and to pH 5 for 30 min was monitored by microarray hybridizations before the application of the stress and at the end of the treatment period, as well as immediately and 30 minutes after conditions were set back to their initial values, 25°C and pH 7, respectively. We also investigated if hysteresis was accompanied with higher resistance to inactivation conditions, 50°C and/or pH 3, as well as more efficient growth at extreme conditions, 43°C and/or pH 4.5.

2012-05-20 | GSE37636 | GEO

Characterization of the ArsRS regulon of Helicobacter pylori

Project description:The human gastric pathogen Helicobacter pylori is extremely well adapted to the highly acidic conditions encountered in the stomach. The pronounced acid resistance of H. pylori relies mainly on the ammonia-producing enzyme urease, however, urease-independent mechanisms are likely to contribute to acid adaptation. Acid-responsive gene regulation is mediated at least in part by the ArsRS two-component system consisting of the essential OmpR-like response regulator ArsR and the non-essential cognate histidine kinase ArsS whose autophosphorylation is triggered in response to low pH. In this study by global transcriptional profiling of an ArsS-deficient H. pylori mutant grown at pH 5.0 we define the ArsR~P- dependent regulon consisting of 110 genes including the urease gene cluster, the genes encoding the aliphatic amidases AmiE and AmiF and the rocF gene encoding arginase. Keywords: Identification of an ArsRS-Regulon

2006-04-01 | GSE4293 | GEO

Transcriptomic analysis of Mtb H37Rv and MtbΔwhiB3 at pH 4.5

Project description:Since WhiB3 expression was shown to be maximally upregulated at pH 4.5 and MtbΔwhiB3 was shown to be defective in survival in Ph 4.5, we did microarray at pH 4.5 so as to study comprehensive role of WhiB3 in regulating gene expression at acidic Ph

2015-12-02 | GSE61579 | GEO

Comparative transcriptome and phenotype analysis of acid-stressed Bacillus cereus strain ATCC 14579

Project description:The food-borne human pathogen Bacillus cereus is found in environments that often have a low pH, such as food and soil. The physiological response upon exposure to several levels of acidity were investigated of B. cereus model strain ATCC 14579, to elucidate the response of B. cereus to acid stress. pH 5.4, pH 5.0, pH 4.8 and pH 4.5 were selected to conduct microarray analyses, based on the differences in physiological response upon exposure to the acid conditions. The transcriptome data revealed response specific profiles. Showing mechanisms induced upon all the different acid down-shocks, such as nitrate reductase and energy production genes, and several genes specifically expressed differentially in mild or lethal levels of acidity, such as F1F0-ATPase and cydAB. Furthermore, mechanisms involved in oxidative stress response were found highly up-regulated in response to both mild and lethal acid stress. The induction of oxidative stress related genes may be a response to the formation of reactive oxygen species by a perturbation of the electron transport chain. Therefore, the formation of hydroxyl radicals and/ or peroxynitrite was monitored upon exposure to the different levels of acidity with a fluorescent probe in a flow cytometer. The formation of these oxidative compounds was shown to be specific for lethal pHs and a model to relate radical formation with the observed transcriptome profiles was proposed. Per acid down-shock three exposure times (i.e., 10, 30 and 60 min) were each compared with non-exposed cells (i.e., t0). In total 4 different acid down-shocks were applied, pH 5.4, pH 5.0, pH 4.8 and pH 4.5. The experiments were performed in duplicate and the duplicate samples were hybridised with a dye-swap.

2010-06-25 | E-GEOD-13711 | biostudies-arrayexpress

Comparative transcriptome and phenotype analysis of acid-stressed Bacillus cereus strain ATCC 10987

Project description:The food-borne human pathogen Bacillus cereus is found in environments that often have a low pH, such as food and soil. The physiological response upon exposure to several levels of acidity were investigated of B. cereus model strain ATCC 10987, to elucidate the response of B. cereus to acid stress. pH 5.4, pH 5.0, pH 4.8 and pH 4.5 were selected to conduct microarray analyses, based on the differences in physiological response upon exposure to the acid conditions. The transcriptome data revealed response specific profiles. Showing mechanisms induced upon all the different acid down-shocks, such as nitrate reductase and energy production genes, and several genes specifically expressed differentially in mild or lethal levels of acidity, such as F1F0-ATPase and cydAB. Furthermore, mechanisms involved in oxidative stress response were found highly up-regulated in response to both mild and lethal acid stress. The induction of oxidative stress related genes may be a response to the formation of reactive oxygen species by a perturbation of the electron transport chain. Therefore, the formation of hydroxyl radicals and/ or peroxynitrite was monitored upon exposure to the different levels of acidity with a fluorescent probe in a flow cytometer. The formation of these oxidative compounds was shown to be specific for lethal pHs and a model to relate radical formation with the observed transcriptome profiles was proposed. Per acid down-shock three exposure times (i.e., 10, 30 and 60 min) were each compared with non-exposed cells (i.e., t0). In total 4 different acid down-shocks were applied, pH 5.4, pH 5.0, pH 4.8 and pH 4.5. The experiments were performed in duplicate and the duplicate samples were hybridised with a dye-swap.

2010-06-25 | E-GEOD-13729 | biostudies-arrayexpress

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