Strategies to Enhance Food Safety: Characterization of Microcins and Bacteriophages

从健康和经济的角度来看，控制食品中细菌污染的能力都具有极其重要的意义。2012年秋季，艾伯塔省布鲁克斯的XL Foods爆发了O157：H7大肠杆菌疫情，导致加拿大有史以来最大规模的食品召回。虽然没有死亡与那次疫情有关，但其经济影响是惊人的。2011年，欧洲爆发了一场类似的大肠杆菌疫情，导致数千人感染，近50人死亡。虽然食品安全显然是一个主要的全球问题，但在食品中添加化学添加剂也受到了审查。公共部门对更天然、加工更少的食品的需求越来越大。我的研究项目与国王大学学院的本科生一起，直接解决了这个问题。我们正在研究自然如何控制细菌种群，并采用这些策略来开发用于食品腐败和病原菌生物控制的新制剂。我们的研究集中在以下几个问题上：如何利用天然产生的有毒多肽(微球蛋白)来杀灭病原菌，如何利用噬菌体或其蛋白来选择性地消除食品腐败菌。我们的第一个项目涉及研究一种名为微蛋白N(MccN)的小蛋白的结构和作用方式。MccN是由大肠杆菌自然产生的一种自卫手段，可以杀死致病的大肠杆菌和沙门氏菌。具体地说，我们正在研究这种化合物的三维结构，并探索它如何靶向和杀死其他细菌，以便更好地了解它作为生物保鲜剂的潜在用途。我们的第二个研究项目集中在鉴定能够杀死各种卡诺氏菌的噬菌体。虽然这些细菌不是致病菌，但它们与肉类产品的变质有关。通过鉴定这些噬菌体和它们的裂解蛋白，我们将了解它们作为生物控制剂的作用，以延长包装肉类和鱼类产品的货架期。

The ability to control bacterial contamination in food is of extreme significance from both a health and economic perspective. An E. coli O157:H7 outbreak at XL Foods (Brooks, Alberta) in the fall of 2012 resulted in the largest ever food recall in Canada. While no deaths were linked to that outbreak, the economic repercussions were staggering. In 2011, a similar E. coli outbreak in Europe was responsible for thousands of infections and nearly 50 deaths. While food safety is clearly a major global concern, the addition of chemical additives to food is also under scrutiny. There is an increasing desire within the public sector for foods that are more natural and minimally processed. My research program, with undergraduate students at The King's University College, directly addresses this issue. We are studying how nature controls bacterial populations and adapting these strategies to develop new agents for the biocontrol of food spoilage and pathogenic bacteria. Our research is focused on the following questions: how can naturally produced toxic peptides (microcins) be used to kill pathogenic bacteria, and how can bacteriophages or their proteins be used to selectively eliminate food spoilage bacteria. Our first project involves studying the structure and mode of action of a small protein called microcin N (MccN). MccN is produced naturally by E. coli as a means of self-defence and kills pathogenic strains of E. coli and Salmonella. Specifically, we are studying the three dimensional structure of this compound and exploring how it targets and kills other bacteria, in order to better understand its potential use as a biopreservative. Our second research project is focused on characterizing bacteriophages that kill various strains of Carnobacteria. While these bacteria are not pathogenic, they are associated with spoilage of meat products. By characterizing these phages and their lysin proteins, we will understand their role as biocontrol agents to extend the shelf life of packaged meat and fish products.