Survival and adaptation of foodborne bacterial pathogens in the food processing environment

几种细菌病原体与食品加工有关，可导致食品对人类消费不安全。拟议的研究计划将使用重要的食源性病原体单核细胞增生李斯特菌（Lm）来研究生物体的生理学如何影响食品加工环境中的生存，定植和持久性。该研究计划的长期目标是根据对Lm在暴露于与食品加工相关的不利条件期间和之后的应激反应的基本理解，提出改进的食品保存和卫生策略。我们将研究在不同温度和营养条件下影响Lm在卷心菜和不锈钢表面附着的因素，Lm和竞争生物体之间的相互作用反映了行业条件。进一步表征鉴定的耐热插入Lm突变体也提出了确定这种表型性状背后的机制。此外，我们的插入突变体库（约4000个突变体在食品环境Lm背景）将被筛选的突变体与附着缺陷，以阐明参与表型特征的因素（基因）。将在选定的突变体中鉴定转座子中断基因的位置，然后与野生型相比表征其表型，以确定中断基因的作用。在存在或不存在共培养物的情况下，将在模型实验中比较选定的临床和食品Lm菌株（和突变体），以确定其对不利条件的抗性，定殖表面和交叉污染食物的能力以及对常见清洁剂和消毒剂的敏感性。 传统的培养方法，显微镜（电子，共聚焦，荧光和光）和转录和蛋白质组学分析将用于评估特定基因的存活，损伤，附着和表达。有关Lm生存和适应食品和食品加工环境条件的因素的新信息可用于设计新的控制策略

Several bacterial pathogens are associated with food processing and can cause foods to become unsafe for human consumption. The proposed research program will use the significant foodborne pathogen, Listeria monocytogenes (Lm), to investigate how the physiology of the organism affects survival, colonisation and persistence in the food processing environment. The long term objective of the research program is to come up with improved strategies for food preservation and sanitation based on a fundamental understanding of the stress response of Lm during and after exposure to adverse conditions associated with food processing.In this research program, we will investigate factors influencing the attachment of Lm to cabbage and stainless steel surfaces under different temperature and nutritional conditions and the interactions between Lm and competing organisms reflecting conditions in the industry. Further characterization of an identified thermotolerant insertional Lm mutant is also proposed to determine the mechanisms behind this phenotypic trait. Also, our insertional mutant library (~ 4000 mutants in a food environmental Lm background) will be screened for mutants with attachment deficiencies to elucidate factors (genes) involved in the phenotypic characteristic. The location of the transposon interrupted gene will be identified in selected mutants followed by characterization of their phenotypes in comparison to the wild-type to determine the effect of the interrupted gene. Selected clinical and food Lm strains (and mutants) in the presence or absence of co-cultures will be compared in model experiments to determine their resistance to adverse conditions, ability to colonise surfaces and become cross-contaminated to foods and susceptibility to common cleaners and sanitisers.  Traditional culture methods, microscopy (electron, confocal, fluorescence and light) and transcriptional and proteomic analyses will be used to assess survival, injury, attachment and expression of specific genes. The novel information about factors involved in the survival and adaptation of Lm to conditions found in food products and the food processing environment can be used to devise new control strategies