SubPopulations of Shiga Toxin Producing Escherichia coli: Persistence, Resistance and Pathogenicity

实验微生物学通常假设细菌种群在抗逆性或基因表达方面是同质的。然而，在现实中，纯菌株培养是异质的，与种群主体相比，部分细胞处于休眠(持久)状态，抵抗力增强。此外，休眠细胞在培养过程中会被忽略，因为它们要么失败，要么生长迟缓。从进化的角度来看，持续状态是一种“更好的对冲”，即在种群条件变得不利的情况下，一定比例的细胞将在较长的时间内存活。到目前为止，大多数关于持久性的研究都是关于抗生素治疗后残留的人群。然而，在更广泛的环境中，如土壤和食品系统，如经高压处理的食品，经常会遇到持久性。残留种群对食品安全的重要性尚不清楚，尽管病原体重新生长或毒力增强的可能性都是*。在拟议的研究计划中，我们将研究产生志贺毒素的志贺毒素的休眠状态(持久性、VBNC和耐受性)。志贺毒素是一类重要的临床和食源性病原体。将首次在STEC中研究持久状态，并确定诱导或打破休眠状态的触发因素。相关的将是来自土壤微生物群*和最终控制病原体的根际：植物相互作用的持久调节因素。这将是第一次展示噬菌体如何影响持久状态，从而导致噬菌体和宿主的长期生存。对持续状态的研究将使用最先进的成像技术和微流体相结合，从而能够在*单细胞水平上进行操纵/观察。处于持续状态的细胞将被产生和收获，以便于研究休眠在抵抗高压和裂解噬菌体方面的作用，以及环境的持久性。这项研究的影响可能是广泛的。从学术的角度*我们将对原噬菌体与宿主的相互作用有更深入的了解。在应用方面，这项研究将提供数据来评估环境和食品系统中的持久细胞所代表的食品安全风险。到目前为止，风险分析经常指定特定的原木减少，以验证干预措施(例如，巴氏杀菌)的*有效性，而不考虑*剩余幸存者。虽然残留物的含量很低，但在储存过程中可能会生长，或者在宿主内变得更具致病力。这项研究将提供数据来评估这种风险，并通过打破休眠状态来引导更有效的病原体控制策略。

Experimental*microbiology typically assumes bacterial populations are homogenous with*respect to resistance to stress or gene expression. However, in reality pure*strain cultures are heterogeneous with a proportion of cells existing in a*dormant (persistent) state that have enhanced resistance compared to the main*body of the population. Moreover, dormant cells are missed during culturing as*they either fail or experience delayed growth. In evolutionary terms the*persistent state is a kind of “bet hedging” whereby a proportion of cells will*survive over extended periods should conditions for the population become*adverse. To date, the majority of studies relating to persistence has been with*respect to residual populations remaining after antibiotic treatment. Yet,*persistence is commonly encountered in the wider environment such as soil, and*food systems, such as foods treated with high pressure processing. The*significance of residual populations with respect to food safety is unknown*although the potential for the re-growth of pathogens or enhanced virulence are*both possibilities. In the proposed research program we will look at the*dormant (persistent, VBNC and tolerant) state in Shiga Toxin producing*Escherichia coli (STEC) a class of significant clinical and foodborne*pathogens. For the first time, the persistent state will be investigated in*STEC and the triggers that both induce or break the dormant state identified.*Of relevance will be the regulators of persistence derived from soil microbiota*and rhizosphere that ultimately control pathogen:plant interactions. For the*first time, it will be demonstrated how prophage influences the persistent state*leading to mutual long term survival of phage and host. Studies of the*persistent state will use state-of-the-art imaging techniques in*combination with microfluidics that enable manipulation/ observation at the*single cell level. Cells in the persistent state will be generated and*harvested to facilitate studies on the role of dormancy in resistance to high*pressure and lytic phages, in addition to environmental persistence. The impact*of the research is potentially wide reaching. From an academic standpoint*greater insights into prophage host interactions will be obtained. On an*application side the research will provide data to assess the food safety risks*represented by persister cells in the environment and food systems. To date,*risk analysis has frequently designated a specified log reduction to verify the*efficacy of interventions (for example, pasteurization) without taking into*account residual survivors. Although present at low levels, residual survivors could grow during storage or become more virulent within the host. The research will provide data to*assess such risks and moreover lead to more effective pathogen control*strategies through breaking of the dormant state.******