Elucidating the factors and mechanisms influencing the formation of biofilms in food systems

*背景：随着加拿大生产和分销系统的不断扩大，食源性病原体有多个进入我们食品系统的入口。生物膜(附着在表面并生长在表面上的各种微生物)与食源性疾病暴发的联系正在上升，因为它们无处不在，对卫生和清除尝试的抵抗力很强。开发针对生物膜的控制策略的努力并不成功；因此，有必要提供更多关于生物膜如何在压力下存活的信息。我的发现基金研究旨在推动这些知识的发展，长期目标是为行业制定战略，帮助防止疫情爆发。我的研究重点是病原菌在受到自然宿主胃肠道外经历的应激预适应后，在暴露于抗菌治疗时所使用的适应性应激反应。在这些瞬变的环境中(例如，在生产、运输、储存期间)，细菌遇到各种次优条件(例如，温度滥用、pH值、低营养)，挑战它们适应更耐压力的形式。生物膜可能是抗逆性的关键；然而，它们的作用尚不清楚，共存于复杂生物膜群落中的其他生物所扮演的角色(S)也是如此。因此，我的研究计划有两个长期目标：1)阐明与生物膜和细菌对抗菌剂、纳米颗粒和环境应激源的适应性耐受有关的生理和分子机制；2)提高对应激事件期间致病和非致病生物膜形成生物之间的群落水平反应和交叉保护相互作用的理解。我们将使用已知病原体来阐明暴露在两个压力阶段的细菌和生物膜的反应，利用蛋白质组学确定的反应--类似于食品生产链中的“条件”压力阶段(低温和缓慢生长)，然后是“施加”压力阶段(即，抗菌剂或纳米颗粒)。在测试生物体中诱导被认为在抗逆性中发挥作用的蛋白质的突变，将使功能(基因表达和生存)分析能够确定哪些反应元件是关键的。然后，这些蛋白质将在暴露在压力下的生物膜群落中进行探测，以确定它们在更复杂的系统中的功能。对微生物应激反应途径的全面了解将为工程生物膜控制策略确定分子靶标。这项研究给加拿大带来的其他好处包括改善食品供应的安全，以及培训食品安全领域的下一代科学家，以支持农业食品部门和科学领域的工业增长。

***Background. With expanding production and distribution systems in Canada, foodborne pathogens have multiple access points into our food system. Linkages of biofilms (diverse microorganisms which attach to, and grow on, surfaces) to outbreaks of foodborne disease are on the rise due to their ubiquity and their resilience to sanitization and removal attempts. Efforts to derive biofilm-specific control strategies have not been successful; thus, more information on how biofilms survive stress is necessary. My discovery grant research seeks to advance such knowledge, with the long-range goal of developing strategies for industry to help prevent outbreaks.*******Program.  My research focuses on adaptive stress responses used by pathogenic bacteria when exposed to antimicrobial treatments after having been pre-conditioned by stresses experienced outside of the gastrointestinal tracts of their natural hosts. In these transient environments (e.g., during production, transport, storage) bacteria encounter various sub-optimal conditions (e.g., temperature abuse, pH, low nutrients), challenging them to adapt to a more stress-resistant form. Biofilms may be key in stress resistance; however, their role remains unclear, as do the role(s) played by other organisms that co-exist within complex biofilm communities. My research program therefore has two long-term objectives: 1) to elucidate physiological and molecular mechanisms involved in biofilm and bacterial adaptive resistance to antimicrobial agents, nanoparticles and environmental stressors, and 2) to improve the understanding of community-level responses and cross-protective interactions between pathogenic and non-pathogenic biofilm-forming organisms during stress events. Experiments will be conducted using known pathogens to elucidate responses, determined using proteomics, in bacteria and biofilms exposed to two phases of stress - a "conditioning" stress phase (low temperature and slow growth) like that found in the food production chain, followed by an "imposed" stress phase (i.e., antimicrobials or nanoparticles). Inducing mutations in proteins thought to play a role in stress resistance in the test organisms will allow functional (gene expression and survival) analyses to confirm which response elements are critical. These proteins will then be probed in biofilm communities exposed to stresses to determine their function in more complex systems. A comprehensive understanding of microbial stress response pathways will identify molecular targets for engineered biofilm control strategies. Other benefits to Canada resulting from this research includes improving the safety of the food supply, as well as training the next generation of scientists in the area of food safety to support industry growth in the agri-food sector as well as the sciences.