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Integrated transcriptomic and proteomic analysis of the physiological response of Escherichia coli O157:H7 Sakai to steady-state conditions of cold and water activity stress.

ABSTRACT: An integrated transcriptomic and proteomic analysis was undertaken to determine the physiological response of Escherichia coli O157:H7 Sakai to steady-state conditions relevant to low temperature and water activity conditions experienced during meat carcass chilling in cold air. The response of E. coli during exponential growth at 25 °C a(w) 0.985, 14 °C a(w) 0.985, 25 °C a(w) 0.967, and 14 °C a(w) 0.967 was compared with that of a reference culture (35 °C a(w) 0.993). Gene and protein expression profiles of E. coli were more strongly affected by low water activity (a(w) 0.967) than by low temperature (14 °C). Predefined group enrichment analysis revealed that a universal response of E. coli to all test conditions included activation of the master stress response regulator RpoS and the Rcs phosphorelay system involved in the biosynthesis of the exopolysaccharide colanic acid, as well as down-regulation of elements involved in chemotaxis and motility. However, colanic acid-deficient mutants were shown to achieve comparable growth rates to their wild-type parents under all conditions, indicating that colanic acid is not required for growth. In contrast to the transcriptomic data, the proteomic data revealed that several processes involved in protein synthesis were down-regulated in overall expression at 14 °C a(w) 0.985, 25 °C a(w) 0.967, and 14 °C a(w) 0.967. This result suggests that during growth under these conditions, E. coli, although able to transcribe the required mRNA, may lack the cellular resources required for translation. Elucidating the global adaptive response of E. coli O157:H7 during exposure to chilling and water activity stress has provided a baseline of knowledge of the physiology of this pathogen.

SUBMITTER: Kocharunchitt C

PROVIDER: S-EPMC3270098 | biostudies-literature | 2012 Jan

REPOSITORIES: biostudies-literature

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Integrated transcriptomic and proteomic analysis of the physiological response of Escherichia coli O157:H7 Sakai to steady-state conditions of cold and water activity stress.

Kocharunchitt Chawalit C King Thea T Gobius Kari K Bowman John P JP Ross Tom T

Molecular & cellular proteomics : MCP 20111018 1

An integrated transcriptomic and proteomic analysis was undertaken to determine the physiological response of Escherichia coli O157:H7 Sakai to steady-state conditions relevant to low temperature and water activity conditions experienced during meat carcass chilling in cold air. The response of E. coli during exponential growth at 25 °C a(w) 0.985, 14 °C a(w) 0.985, 25 °C a(w) 0.967, and 14 °C a(w) 0.967 was compared with that of a reference culture (35 °C a(w) 0.993). Gene and protein expressio ...[more]

PMID: 22008207

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Project description:Enterohemeorrhagic Escherichia coli is a leading cause of foodborne illness, with the majority of cases linked to foods of bovine origin. Currently, no completely effective method for controlling this pathogen during carcass processing exists. Understanding how this pathogen behaves under those stress conditions experienced on the carcass during chilling in cold air could offer opportunities for development or improvement of effective decontamination processes. Therefore, we studied the growth kinetics and physiological response of exponential phase E. coli O157:H7 Sakai cultures upon an abrupt downshift in temperature and water activity (from 35 °C aw 0.993 to 14 °C aw 0.967). A parallel Biolog study was conducted to follow the phenotypic responses to 190 carbon sources. Exposure of E. coli to combined cold and water activity stresses resulted in a complex pattern of population changes. This pattern could be divided into two main phases, including adaptation and regrowth phases, based on growth kinetics and clustering analyses. The transcriptomic and proteomic studies revealed that E. coli exhibited a "window" of cell susceptibility (i.e. weaknesses) during adaptation phase. This included apparent DNA damage, the downregulation of molecular chaperones and proteins associated with responses to oxidative damage. However, E. coli also displayed a transient induction in the RpoE-controlled envelope stress response and activation of the master stress regulator RpoS and the Rcs phosphorelay system involved in colanic acid biosynthesis. Increased expression was observed for several genes and/or proteins involved in DNA repair, protein and peptide degradation, amino acid biosynthesis, and carbohydrate catabolism and energy generation. Furthermore, the Biolog study revealed reduced carbon source utilization during adaptation phase, indicating the disruption of energy-generating processes. This study provides insight into the physiological response of E. coli during exposure to combined cold and water activity stress, which could be exploited to enhance the microbiological safety of carcasses and related foods.

Dataset Information

Integrated transcriptomic and proteomic analysis of the physiological response of Escherichia coli O157:H7 Sakai to steady-state conditions of cold and water activity stress.

Publications

Integrated transcriptomic and proteomic analysis of the physiological response of Escherichia coli O157:H7 Sakai to steady-state conditions of cold and water activity stress.

Similar Datasets

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