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Heat shock and prolonged heat stress attenuate neurotoxin and sporulation gene expression in group I Clostridium botulinum strain ATCC 3502.

ABSTRACT: Foodborne pathogenic bacteria are exposed to a number of environmental stresses during food processing, storage, and preparation, and in the human body. In order to improve the safety of food, the understanding of molecular stress response mechanisms foodborne pathogens employ is essential. Many response mechanisms that are activated during heat shock may cross-protect bacteria against other environmental stresses. To better understand the molecular mechanisms Clostridium botulinum, the causative agent of botulism, utilizes during acute heat stress and during adaptation to stressfully high temperature, the C. botulinum Group I strain ATCC 3502 was grown in continuous culture at 39°C and exposed to heat shock at 45°C, followed by prolonged heat stress at 45°C to allow adaptation of the culture to the high temperature. Growth in continuous culture was performed to exclude secondary growth phase effects or other environmental impacts on bacterial gene transcription. Changes in global gene expression profiles were studied using DNA microarray hybridization. During acute heat stress, Class I and III heat shock genes as well as members of the SOS regulon were activated. The neurotoxin gene botA and genes encoding the neurotoxin-associated proteins were suppressed throughout the study. Prolonged heat stress led to suppression of the sporulation machinery whereas genes related to chemotaxis and motility were activated. Induced expression of a large proportion of prophage genes was detected, suggesting an important role of acquired genes in the stress resistance of C. botulinum. Finally, changes in the expression of a large number of genes related to carbohydrate and amino acid metabolism indicated remodeling of the cellular metabolism.

SUBMITTER: Selby K

PROVIDER: S-EPMC5413062 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Heat shock and prolonged heat stress attenuate neurotoxin and sporulation gene expression in group I Clostridium botulinum strain ATCC 3502.

Selby Katja K Mascher Gerald G Somervuo Panu P Lindström Miia M Korkeala Hannu H

PloS one 20170502 5

Foodborne pathogenic bacteria are exposed to a number of environmental stresses during food processing, storage, and preparation, and in the human body. In order to improve the safety of food, the understanding of molecular stress response mechanisms foodborne pathogens employ is essential. Many response mechanisms that are activated during heat shock may cross-protect bacteria against other environmental stresses. To better understand the molecular mechanisms Clostridium botulinum, the causativ ...[more]

PMID: 28464023

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Project description:Profound understanding of the mechanisms foodborne pathogenic bacteria utilize in adaptation to the environmental stress they encounter during food processing and storage is of paramount importance in design of control measures. Chill temperature is a central control measure applied in minimally processed foods; however, data on the mechanisms the foodborne pathogen Clostridium botulinum activates upon cold stress are scarce. Global gene expression analysis on the C.M-BM- botulinum ATCC 3502 strain upon temperature downshift from 37 M-BM-0C to 15M-BM- M-BM-0C was performed to identify the cold-responsive gene set of this organism. Significant up- or down-regulation of 16 and 11 genes, respectively, was observed already 1 h after the cold shock. At 5 h after the temperature downshift, 199 and 210 genes were up- and down-regulated, respectively. Thus, the cold shock rapidly affected the expression of a gene set of a relatively small size, indicating a targeted acute response to cold shock, whereas extensive metabolic remodeling took place after prolonged exposure to cold. Induction of genes related to fatty acid biosynthesis, oxidative stress response, and iron uptake and storage was observed, in addition to mechanisms previously characterized as cold-tolerance related in bacteria. Furthermore, induction of several uncharacterized DNA-binding transcriptional regulator-encoding genes was observed, suggesting involvement of novel regulatory mechanisms in the cold shock response of C.M-BM- botulinum. The role of such regulatory proteins, CBO0477 and CBO0558A, in cold tolerance of C.M-BM- botulinum ATCC 3502 was demonstrated by the deteriorated growth of mutants of the respective genes at 17M-BM- M-BM-0C. C. botulinum ATCC 3502 wild type cold-shocked vs. pre-cold-shock; 3 replicates; growth at 37C in TPGY broth batch culture and subjected to cold shock to 15C; sampling at mid-log growth phase before cold shock, and 1 h and 5 h after temperature downshift to 15C (= 3 time points). Dye-swapped hybridization.

Dataset Information

Heat shock and prolonged heat stress attenuate neurotoxin and sporulation gene expression in group I Clostridium botulinum strain ATCC 3502.

Publications

Heat shock and prolonged heat stress attenuate neurotoxin and sporulation gene expression in group I Clostridium botulinum strain ATCC 3502.

Similar Datasets

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