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

根据加拿大食品检验局的数据，每年有1100万例食源性疾病。因此，菠菜和胡萝卜汁成为今年秋天的头条新闻。为了更好地控制食品中的微生物，我们必须在分子水平上了解抗菌系统的功效和微生物对它们的生理反应。微生物通过诱导合成一种称为应激蛋白的蛋白质子集来对亚致死处理和胁迫作出反应。几种应激蛋白已被鉴定出用于各种应激，有些甚至被多种应激诱导。消费者对方便、最低限度加工、更安全、保质期更长食品的需求，最好是通过应用被称为“跨栏技术”的多种抗菌系统来实现。然而，我们对“食物乳杆菌对环境胁迫的适应”的研究表明，不同顺序的抗菌系统的生存水平不同。当“障碍”同时应用时，效果最好（Lemay et al., 2000）。Int。[j] .食品微生物学杂志。55:249-253。这些结果表明，预诱导应激蛋白或一般应激反应（如RpoS）有助于提高微生物的抗性和适应性。我们的尝试是证明，根据它们在细胞中的特定功能，某些应激蛋白可能对不一定诱导其产生的应激提供交叉保护。由于并非所有的抗菌系统在食品加工中同时使用，因此研究抗菌系统之间的交叉保护和微生物适应具有重要意义。最终，将确定抗菌系统的最佳组合。根据NSERC为所有加拿大人服务的愿景，这项研究将通过减少食源性疾病爆发，对我们农业食品工业的社会经济方面和公共卫生产生积极影响。

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.