Bacteriocins of the Intestinal Bacteroidales

描述（由申请人提供）：哺乳动物肠道容纳了一个复杂而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了共生，共生，有时致病的关系。为了在这个人口密集的环境中定居，这些细菌还必须与其他微生物居民建立互惠和对抗的关系。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，但很少有研究检查该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，约占该生态系统生物总数的20%。我们的长期目标是阐明允许拟杆菌在哺乳动物肠道中定植并持续存在的微生物因素和机制，从而为宿主提供益处。我们也有兴趣了解促成该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。该应用程序解决了细菌编码的抗菌分子的生产，称为细菌素。肠道拟杆菌属产生细菌素的报道早在多年前就有报道，但没有克隆出细菌素基因，也没有描述细菌素的作用机制。此外，细菌素的产生对肠道生态系统中种群动态和微生物多样性的贡献尚未得到探讨。本提案中概述的实验将在分子水平上识别和表征由脆弱拟杆菌型菌株产生的众多细菌素，以了解该目细菌产生的细菌素的广度和类型。目的2包括对哺乳动物免疫细胞产生的分子中含有膜攻击复杂基序的独特细菌素进行更深入的分析。相似的分子被不同的拟杆菌门物种的基因组编码，这种细菌素可能是这些拟杆菌门物种共同使用的防御/攻击分子，它们大多生活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。体外系统代表空间结构化和非结构化社区将进行分析。此外，我们将使用非生物小鼠肠道定植模型进行实验，以确定这种细菌素在天然哺乳动物肠道生态系统中的相关性。这些实验将确定这种细菌素是否促进微生物多样性，是否促进菌株入侵已建立的生态系统，以及它在阻止竞争敏感菌株定植方面的作用。这些综合研究将全面分析这些抗菌分子及其在密集和竞争的肠道生态系统中产生的意义。

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.