Bacterial pathogens in food processing: Studies of the survival and control of Listeria monocytogenes to enhance food safety

单核细胞增多性李斯特菌是一种严重危害食品安全的细菌。细菌病原体可能会在食品加工表面持续较长时间，从而增加污染食品的机会。加拿大人在2008年亲身经历了这种情况的危险，当时食用安大略省一家加工厂的受污染午餐肉导致56例李斯特菌病和22例死亡。最近，美国爆发的疫情震惊了消费者，已有23人(116例)因食用来自科罗拉多州的受污染的新鲜哈密瓜而死亡。显然，我们需要更好的干预策略。 拟议研究计划的长期目标是阐明导致单核细胞增多性李斯特菌在食品加工环境中持续存在的机制。拟议的计划将建立在我的实验室正在进行的工作的基础上。 我的研究团队将在未来几年解决的具体短期目标或研究问题如下： 1.单核细胞增多性乳杆菌耐脱水的机制是什么？ 2.在长期的干燥过程中，是否形成了抗干燥的亚群？ 3.生物膜形成的机制是什么？在有或没有竞争微生物的情况下，生物膜对单核细胞增多性乳杆菌的生存和从低相对湿度的食品加工环境中去除起到什么作用？ 4.细菌在不同环境条件下干燥存活的动力学是什么？ 随着我们对单核细胞增多性乳杆菌的生存策略有了基本的了解，我们的发现将导致制定专注于开发改进的去除策略的应用研究项目。换句话说，这项研究将通过改进卫生和食品加工战略以及为加拿大人提供更安全的食品来帮助食品工业。

Listeria monocytogenes is a serious bacterial hazard which threatens food safety. The bacterial pathogen can persist for extended periods of time on food processing surfaces to increase the chance of contaminating food products. Canadians experienced first hand the danger of this scenario in 2008, where consumption of contaminated luncheon meats from one processing facility in Ontario caused 56 cases of listeriosis and 22 deaths. Lately, an outbreak in the US has shocked consumers as 23 people (116 cases) have died from consuming contaminated fresh cantaloupe from Colorado. Clearly, we need better intervention strategies. The long term objective of the proposed research program is to elucidate the mechanisms responsible for the persistence of L. monocytogenes in the food processing environment. The proposed program will build on the on-going work in my laboratory. The specific short term objectives or research questions, which my research team will address in the coming years, are as follows: 1. What are the mechanisms of desiccation tolerance observed in L. monocytogenes? 2. Does a desiccation resistant subpopulation develop during long-term desiccation? 3. What are the mechanisms of biofilm formation and what role does biofilm play for L. monocytogenes' survival and removal from food processing environments with low RH in the presence or absence of competing microorganisms? 4. What is the kinetics of the bacterium's desiccation survival under different environmental conditions? As we gain a fundamental understanding of L. monocytogenes' survival strategies, our discoveries will lead to the formulation of applied research projects focused on developing improved removal strategies. In other words this research will help the food industry by leading to improved sanitation and food processing strategies as well as to safer food products for Canadians.