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应激或基因表达方面是同质的。然而，在现实中，纯抑制培养物是异质的，与群体的主体相比，一部分细胞以粘附（持久）状态存在，具有增强的抗性。此外，休眠细胞在培养过程中被遗漏，因为它们要么失败要么经历延迟生长。从进化的角度来看，这种持续状态是一种“赌注对冲”，如果种群的条件变得不利，一定比例的细胞将在较长的时间内存活下来。迄今为止，大多数与持久性相关的研究都是关于抗生素治疗后剩余的残留种群。然而，持久性通常在更广泛的环境中遇到，如土壤和食品系统，如高压加工处理的食品。尽管病原体再生长或增强毒力的可能性都是可能的，但残留种群对食品安全的重要性尚不清楚。在拟议的研究计划中，我们将着眼于休眠（持久，VBNC和耐受）状态下产滋贺毒素大肠杆菌（STEC）的一类重要的临床和食品安全的病原体。这是第一次，持续状态将被调查inSTEC和触发器，都诱导或打破休眠状态identified.Of相关的持久性来自土壤微生物和根际，最终控制病原体：植物相互作用的调节器。这将是第一次，它将证明如何影响噬菌体和宿主的相互长期生存的持久状态。持续状态的研究将使用最先进的成像技术结合微流体技术，使操作/观察在thessingle细胞水平。将产生和收获处于持久状态的细胞，以便于研究休眠在抗高压和溶解性破坏中的作用，以及环境持久性。这项研究的影响可能是广泛的。从学术的角度来看，对原噬菌体与宿主的相互作用将有更深入的了解。在应用方面，该研究将提供数据，以评估环境和食品系统中持久性细胞所代表的食品安全风险.到目前为止，风险分析经常指定一个特定的对数减少，以验证干预措施（例如，巴氏灭菌）的有效性，而不考虑剩余的幸存者。虽然存在于低水平，残留的幸存者可以在储存过程中增长或在宿主体内变得更具毒性。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制定更有效的病原体控制策略。

Experimentalmicrobiology typically assumes bacterial populations are homogenous withrespect to resistance to stress or gene expression. However, in reality purestrain cultures are heterogeneous with a proportion of cells existing in adormant (persistent) state that have enhanced resistance compared to the mainbody of the population. Moreover, dormant cells are missed during culturing asthey either fail or experience delayed growth. In evolutionary terms thepersistent state is a kind of “bet hedging” whereby a proportion of cells willsurvive over extended periods should conditions for the population becomeadverse. To date, the majority of studies relating to persistence has been withrespect to residual populations remaining after antibiotic treatment. Yet,persistence is commonly encountered in the wider environment such as soil, andfood systems, such as foods treated with high pressure processing. Thesignificance of residual populations with respect to food safety is unknownalthough the potential for the re-growth of pathogens or enhanced virulence areboth possibilities. In the proposed research program we will look at thedormant (persistent, VBNC and tolerant) state in Shiga Toxin producingEscherichia coli (STEC) a class of significant clinical and foodbornepathogens. For the first time, the persistent state will be investigated inSTEC and the triggers that both induce or break the dormant state identified.Of relevance will be the regulators of persistence derived from soil microbiotaand rhizosphere that ultimately control pathogen:plant interactions. For thefirst time, it will be demonstrated how prophage influences the persistent stateleading to mutual long term survival of phage and host. Studies of thepersistent state will use state-of-the-art imaging techniques incombination with microfluidics that enable manipulation/ observation at thesingle cell level. Cells in the persistent state will be generated andharvested to facilitate studies on the role of dormancy in resistance to highpressure and lytic phages, in addition to environmental persistence. The impactof the research is potentially wide reaching. From an academic standpointgreater insights into prophage host interactions will be obtained. On anapplication side the research will provide data to assess the food safety risksrepresented by persister cells in the environment and food systems. To date,risk analysis has frequently designated a specified log reduction to verify theefficacy of interventions (for example, pasteurization) without taking intoaccount 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 toassess such risks and moreover lead to more effective pathogen controlstrategies through breaking of the dormant state.