Bacteriocins of the Intestinal Bacteroidales

描述（由申请人提供）：哺乳动物肠道内存在复杂多样的微生物生态系统，其中微生物成员与其哺乳动物宿主建立共生、共生和有时致病的关系。为了在这个人口稠密的环境中定居，这些细菌还必须与其他微生物居民建立互利和拮抗关系。最近的研究已经检查了肠道微生物群成员赋予宿主的有益特性，但很少有研究检查了这个生态系统中微生物成员之间存在的重要关系和相互作用。拟杆菌属是人类肠道微生物群的丰富成员，约占该生态系统总生物的20%。我们的长期目标是阐明微生物因素和机制，使拟杆菌属。在哺乳动物肠道内定居并持续存在，为宿主提供益处。我们也有兴趣了解有助于生态系统中微生物多样性的微生物因素，以及我们如何利用这些细菌产生的抗菌分子用于治疗目的或操纵生态系统的组成以积极影响人类健康。本申请涉及细菌编码的抗微生物分子（称为细菌素）的生产。肠道拟杆菌属细菌素的产生。尽管细菌素的基因在许多年前就有报道，但没有克隆细菌素基因，也没有描述其作用机制。此外，细菌素生产的肠道生态系统中的种群动态和微生物多样性的贡献还没有探索。本提案中概述的实验将在分子水平上鉴定和表征脆弱拟杆菌型菌株产生的多种细菌素，以了解该细菌产生的细菌素的广度和类型。目标2包括对一种独特的细菌素进行更深入的分析，这种细菌素具有哺乳动物免疫细胞产生的分子上所含的膜攻击复合物基序。类似的分子由不同拟杆菌属物种的基因组编码，并且这种细菌素可能是这些拟杆菌属物种使用的常见防御/进攻分子，其中大多数栖息在不同的多微生物生态系统中。对于第三个目标，我们将使用MACPF细菌素作为模型进行良好控制的生态学研究。将分析代表空间结构化和非结构化社区的体外系统。此外，我们将进行实验，使用gnotobiotic小鼠肠道定植模型，以确定这种细菌素在自然哺乳动物肠道生态系统的相关性。这些实验将确定这种细菌素是否促进微生物多样性，是否促进菌株侵入已建立的生态系统，以及它在阻止竞争敏感菌株定植方面的作用。这些研究的结合将提供对这些抗菌分子及其在密集和竞争性肠道生态系统中产生的意义的全面分析。

DESCRIPTION (provided by applicant): The mammalian gut houses a complex and diverse microbial ecosystem in which microbial members establish commensal, symbiotic, and sometimes pathogenic relationships with their mammalian host. In order to colonize this densely populated environment, these bacteria must also establish both mutualistic and antagonistic relationships with other microbial inhabitants. Recent studies have examined the beneficial properties conferred to the host by members of the intestinal microbiota, but few studies have examined the important relationships and interactions that exist between the microbial members of this ecosystem. Bacteroides spp. are abundant members of the human intestinal microbiota, accounting for approximately 20% of the total organisms of this ecosystem. Our long term goals are directed toward elucidating microbial factors and mechanisms that allow Bacteroides spp. to colonize and persist in the mammalian intestine where they provide benefits to the host. We are also interested in understanding the microbial factors that contribute to microbial diversity in ths ecosystem and how we may exploit antimicrobial molecules produced by these bacteria for therapeutic purposes or to manipulate the composition of the ecosystem to positively impact human health. This application addresses the production of bacterially-encoded antimicrobial molecules, known as bacteriocins. Bacteriocin production by intestinal Bacteroides spp. was reported many years ago, however, no bacteriocin gene was cloned, nor was the mechanisms of action described. In addition, the contribution of bacteriocin production to population dynamics and microbial diversity in the intestinal ecosystem has not been explored. The experiments outlined in this proposal will identify and characterize the numerous bacteriocins produced by a Bacteroides fragilis type strain at the molecular level to understand the breadth and types of bacteriocins produced by this order of bacteria. Aim 2 includes more in-depth analyses of a unique bacteriocin with a membrane attack complex motif contained on molecules produced by mammalian immune cells. Similar molecules are encoded by the genomes of diverse Bacteroidetes species and this bacteriocin may be a common defensive/offensive molecule used by these Bacteroidetes species, most of which inhabit diverse polymicrobial ecosystems. For the third aim, we will perform well-controlled ecological studies using the MACPF bacteriocin as a model. In vitro systems representing both spatially structured and unstructured communities will be analyzed. In addition, we will perform experiments using a gnotobiotic mouse intestinal colonization model to determine the relevance of this bacteriocin in the natural mammalian intestinal ecosystem. These experiments will determine if this bacteriocin promotes microbial diversity, if it facilitates the invasion of a strain into an established ecosystem, and its role in thwarting colonization of a competing sensitive strain. This combination of studies will provide a comprehensive analysis of these antimicrobial molecules and the significance of their production in the dense and competitive intestinal ecosystem.