Membrane proteins and stress resistance in foodborne bacteria

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The control of bacteria in food processing depends on the knowledge of bacterial resistance to chemical, physical, and biological preservation methods. A detailed characterisation of bacterial stress resistance is particularly required for novel, non-thermal preservation technologies that are currently adopted by the Canadian food industry. Many mechanisms of bacterial stress resistance are almost universally employed by foodborne bacteria. Their role in food processing, however, has opposite meaning when employed by bacteria that are detrimental to food quality and safety (spoilage organisms or pathogens), or when employed by organisms that improve food quality (fermentation organisms or probiotic bacteria). For example, glutamate-based acid resistance of pathogens improves their survival during gastric passage and hence increases their virulence. The same mechanism, glutamate based acid resistance, also improves the survival of probiotics during gastric passage and thus improves their beneficial effect on human health. The applicant's research has recently discovered novel mechanisms for heat and acid resistance in pathogens and probiotics. This proposal will characterize these mechanisms on a molecular and physiological level, and determine their relevance in food and food model system. The short term objectives of this proposal are the characterisation of heat, acid, and salt resistance in two model organisms, Escherichia coli and Lactobacillus reuteri. This improved understanding of bacterial resistance to processes used in food production will benefit Canada by providing novel tools to increase food safety and food quality. The project will train six highly qualified personnel that are available for employment by the Canadian food industry or related sectors after graduation.