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Physiological response of Escherichia coli O157:H7 Sakai to dynamic changes in temperature and water activity as experienced during carcass chilling


King, T and Kocharunchitt, C and Gobius, K and Bowman, JP and Ross, T, Physiological response of Escherichia coli O157:H7 Sakai to dynamic changes in temperature and water activity as experienced during carcass chilling, Molecular and Cellular Proteomics, 15, (11) pp. 3331-3347. ISSN 1535-9476 (2016) [Professional, Refereed Article]

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DOI: doi:10.1074/mcp.M116.063065


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.

Item Details

Item Type:Professional, Refereed Article
Keywords:public health, physiological stress of bacteria
Research Division:Biological Sciences
Research Group:Microbiology
Research Field:Microbiology not elsewhere classified
Objective Division:Health
Objective Group:Public health (excl. specific population health)
Objective Field:Food safety
UTAS Author:Kocharunchitt, C (Mr Chawalit Kocharunchitt)
UTAS Author:Bowman, JP (Associate Professor John Bowman)
UTAS Author:Ross, T (Professor Tom Ross)
ID Code:115156
Year Published:2016
Web of Science® Times Cited:9
Deposited By:Tasmanian Institute of Agriculture
Deposited On:2017-03-08
Last Modified:2017-03-15

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