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Listeria monocytogenes shows temperature-dependent and -independent responses to salt stress, including responses that induce cross-protection against other stresses.

ABSTRACT: The food-borne pathogen Listeria monocytogenes experiences osmotic stress in many habitats, including foods and the gastrointestinal tract of the host. During transmission, L. monocytogenes is likely to experience osmotic stress at different temperatures and may adapt to osmotic stress in a temperature-dependent manner. To understand the impact of temperature on the responses this pathogen uses to adapt to osmotic stress, we assessed genome-wide changes in the L. monocytogenes H7858 transcriptome during short-term and long-term adaptation to salt stress at 7°C and 37°C. At both temperatures, the short-term response to salt stress included increased transcript levels of sigB and SigB-regulated genes, as well as mrpABCDEFG, encoding a sodium/proton antiporter. This antiporter was found to play a role in adaptation to salt stress at both temperatures; ΔmrpABCDEFG had a significantly longer lag phase than the parent strain in BHI plus 6% NaCl at 7°C and 37°C. The short-term adaptation to salt stress at 7°C included increased transcript levels of two genes encoding carboxypeptidases that modify peptidoglycan. These carboxypeptidases play a role in the short-term adaptation to salt stress only at 7°C, where the deletion mutants had significantly different lag phases than the parent strain. Changes in the transcriptome at both temperatures suggested that exposure to salt stress could provide cross-protection to other stresses, including peroxide stress. Short-term exposure to salt stress significantly increased H(2)O(2) resistance at both temperatures. These results provide information for the development of knowledge-based intervention methods against this pathogen, as well as provide insight into potential mechanisms of cross-protection.

SUBMITTER: Bergholz TM

PROVIDER: S-EPMC3318819 | biostudies-other | 2012 Apr

REPOSITORIES: biostudies-other

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Listeria monocytogenes shows temperature-dependent and -independent responses to salt stress, including responses that induce cross-protection against other stresses.

Bergholz Teresa M TM Bowen Barbara B Wiedmann Martin M Boor Kathryn J KJ

Applied and environmental microbiology 20120203 8

The food-borne pathogen Listeria monocytogenes experiences osmotic stress in many habitats, including foods and the gastrointestinal tract of the host. During transmission, L. monocytogenes is likely to experience osmotic stress at different temperatures and may adapt to osmotic stress in a temperature-dependent manner. To understand the impact of temperature on the responses this pathogen uses to adapt to osmotic stress, we assessed genome-wide changes in the L. monocytogenes H7858 transcriptom ...[more]

PMID: 22307309

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Project description:The foodborne pathogen Listeria monocytogenes experiences osmotic stress in many habitats, including foods and the gastrointestinal tract of the host. While osmotic stress induced changes in expression have been investigated for specific genes, identifying and understanding genome-wide temporal changes in the transcriptome due to salt stress will provide insights into how this pathogen adapts to and survives this stress, leading to development of new intervention strategies. To determine the short-term and long-term responses to salt stress, we exposed exponential phase cells of L. monocytogenes H7858 to 6% NaCl in Brain Heart Infusion (BHI) broth at 7°C and 37°C and extracted RNA after 2.5%, 5%, 10%, and 20% of lag phase and during exponential growth in BHI + 6% NaCl, and evaluated temporal changes in transcript levels with microarrays. The temperature dependent short-term response to salt stress included a significant increase in transcript levels of the alternative sigma factor σB, with maximum expression at 2.5-5% of lag phase at 37°C, and at 20% of lag phase at 7°C. Transcript levels of genes known to be regulated by σB, including inlAB, opuCA, glpFK, and gadBC, were significantly upregulated at the same relative time points as σB As indicated by significantly elevated transcript levels during exponential growth in BHI + 6% NaCl, genes encoding proteins involved in purine and pyrimidine synthesis and amino acid biosynthesis are part of the long-term response to salt stress at 37°C. Transcript levels of virulence genes plcA, mpl, actA, and plcB were also significantly upregulated during exponential growth under salt stress at 37°C. Genes encoding proteins involved in protein degradation and stability and cell membrane modifications are part of the long-term response to salt stress at 7°C. Overall, an initial alteration in the transcriptome occurs, decreasing transcript levels of genes encoding proteins involved in energy conversion and metabolism, while increasing transcript levels of those involved in the stress response controlled by σB, followed by a long-term response, including increased expression of genes encoding compatible solute transporters and general stress proteins, facilitating growth under salt stress.

Dataset Information

Listeria monocytogenes shows temperature-dependent and -independent responses to salt stress, including responses that induce cross-protection against other stresses.

Publications

Listeria monocytogenes shows temperature-dependent and -independent responses to salt stress, including responses that induce cross-protection against other stresses.

Similar Datasets

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