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，可能导致食品变得不安全，不适合人类食用。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性李斯特菌(Lm)来研究该生物的生理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在基本了解LM在食品加工过程中和暴露在与食品加工相关的不利条件下的应激反应的基础上，提出改进的食品保存和卫生策略。在本研究计划中，我们将调查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，以及LM与反映行业条件的竞争生物之间的相互作用。还建议对已鉴定的耐热插入突变体进行进一步的鉴定，以确定这种表型特征背后的机制。此外，我们的插入突变体文库(约4000个食品环境LM背景中的突变)将被筛选出具有附着缺陷的突变，以阐明与表型特征有关的因素(基因)。转座子中断基因的位置将在选定的突变体中确定，然后与野生型进行比较，以确定其表型，以确定中断基因的影响。选定的临床和食品LM菌株(和突变体)在有或没有共培养的情况下将在模型实验中进行比较，以确定它们对不利条件的抵抗力、在表面定居和与食物交叉污染的能力以及对常见清洁剂和消毒剂的敏感性。与传统的培养方法相比，将使用显微镜(电子、共聚焦、荧光和光)以及转录和蛋白质组分析来评估特定基因的存活、损伤、附着和表达。有关光肩星天牛生存和适应食品和食品加工环境条件的因素的新信息可以用来设计新的控制策略。

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