Survival and adaptation of foodborne bacterial pathogens in the food processing environment

点击翻译按钮获取中文摘要

Several bacterial pathogens are associated with food processing and can cause foods to become unsafe for human consumption. The proposed research program will use the significant foodborne pathogen, Listeria monocytogenes (Lm), to investigate how the physiology of the organism affects survival, colonisation and persistence in the food processing environment. The long term objective of the research program is to come up with improved strategies for food preservation and sanitation based on a fundamental understanding of the stress response of Lm during and after exposure to adverse conditions associated with food processing.In this research program, we will investigate factors influencing the attachment of Lm to cabbage and stainless steel surfaces under different temperature and nutritional conditions and the interactions between Lm and competing organisms reflecting conditions in the industry. Further characterization of an identified thermotolerant insertional Lm mutant is also proposed to determine the mechanisms behind this phenotypic trait. Also, our insertional mutant library (~ 4000 mutants in a food environmental Lm background) will be screened for mutants with attachment deficiencies to elucidate factors (genes) involved in the phenotypic characteristic. The location of the transposon interrupted gene will be identified in selected mutants followed by characterization of their phenotypes in comparison to the wild-type to determine the effect of the interrupted gene. Selected clinical and food Lm strains (and mutants) in the presence or absence of co-cultures will be compared in model experiments to determine their resistance to adverse conditions, ability to colonise surfaces and become cross-contaminated to foods and susceptibility to common cleaners and sanitisers.  Traditional culture methods, microscopy (electron, confocal, fluorescence and light) and transcriptional and proteomic analyses will be used to assess survival, injury, attachment and expression of specific genes. The novel information about factors involved in the survival and adaptation of Lm to conditions found in food products and the food processing environment can be used to devise new control strategies