Efficacy of antimicrobial systems used in foods; understanding the stress-proteins pathways

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According to the Canadian Food Inspection agency, there are 11 millions cases of food borne illnesses every year. Spinach and carrot juice made the headlines this fall for that reason. To improve the control of microorganims in our food supply, we must understand the efficacy of antimicrobial systems and the microbial physiological response to them at the molecular level.Microorganisms respond to sublethal treatments and stresses by inducing the synthesis of a subset of proteins referred to as stress proteins. Several stress proteins have been identified for various stresses and some are even induced by more than one stress. Consumer's demands for convenient, minimally processed, safer foods with extended shelf life, have been best achieved through the application of multiple antimicrobial systems referred to as the "hurdle technology". However, our research on "Adaptation of Lactobacillus alimentarius to environmental stresses" revealed that survival level is different when the antimicrobial systems are applied in different orders. Best results are obtained when the "hurdles" are applied simultaneously (Lemay et al., 2000. Int. J. Food Microbiol. 55:249-253). These results suggest that pre-induction of stress proteins, or the general stress response (ex. RpoS), contributes to a better resistance and adaptation of microorganisms. Our attempt is to demonstrate that, depending on their specific function in the cell, certain stress proteins may provide cross protection to stresses that do not necessary induce their production. Because not all the antimicrobial systems are used simultaneously in food processing, it is important to study cross protection and microbial adaptation between antimicrobial systems. Ultimately, optimal combinations of antimicrobial systems will be determined.In line with NSERC vision to serve all Canadians, this research will have a positive impact on socio-economic aspects of our agri-food industry and in public health through a reduction of food borne outbreaks.