Membrane proteins and stress resistance in foodborne bacteria

食品加工中细菌的控制依赖于细菌对化学、物理和生物保存方法的抵抗力的知识。加拿大食品工业目前采用的新型非保暖技术尤其需要对细菌抗逆性进行详细的表征。 食源性细菌几乎普遍采用许多抗细菌胁迫的机制。然而，当它们被危害食品质量和安全的细菌(腐败微生物或病原体)所利用时，或当它们被提高食品质量的微生物(发酵微生物或益生菌)所利用时，它们在食品加工中的作用具有相反的意义。例如，病原体基于谷氨酸的耐酸性提高了它们在胃通过过程中的存活率，从而增加了它们的毒力。同样的机制，基于谷氨酸的耐酸性，也提高了益生菌在胃通过过程中的存活率，从而改善了它们对人类健康的有益效果。 申请人的研究最近发现了病原体和益生菌耐热和耐酸的新机制。这项提议将从分子和生理水平描述这些机制，并确定它们在食品和食品模型系统中的相关性。这项建议的短期目标是研究两种模式生物--大肠杆菌和路氏乳杆菌--的耐热、耐酸和耐盐性。 这种对食品生产过程中细菌耐药性的更好理解将为加拿大提供提高食品安全和食品质量的新工具，使加拿大受益。该项目将培训六名高素质的人员，毕业后可供加拿大食品业或相关部门就业。

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.