Symbiosis of E. coli and the Intestinal Microbiota in a Mouse Model

小鼠模型中大肠杆菌与肠道微生物群的共生

• 批准号: 8302475
• 负责人: TYRRELL CONWAY
• 金额: $ 1.82万
• 依托单位: UNIVERSITY OF OKLAHOMA
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8302475
• 关键词: Ablation; Address; Affect; Anaerobic Bacteria; Anaerobiosis; Animal Model; Attention; Bacterial Adhesins; Bacteroidetes; Cecum; Cells; Coculture Techniques; Communities; Complex; Coupled; Dietary Fiber; Digestion; Disease Resistance; Dissection; Ecosystem; Escherichia coli; Exhibits; Flagella; Fluorescent in Situ Hybridization; Food Webs; Foundations; Genetic; Genomics; Goals; Gram-Negative Bacteria; Growth; Health; Host resistance; Human; Human Microbiome; Image; In Situ; Individual; Intestines; K antigen; Kinetics; Lasers; Learning; Life; Lipopolysaccharides; Mass Spectrum Analysis; Measures; Metabolic; Metabolism; Microbe; Microscopic; Modeling; Molecular; Mucous body substance; Mus; Nutrient; Nutritional; Nutritional Study; O Antigens; Oklahoma; Organism; Oxygen; Oxygen measurement, partial pressure, arterial; Pathway interactions; Pattern; Phylogenetic Analysis; Phylogeny; Play; Polysaccharides; Population; Process; Property; Research; Research Design; Resources; Role; Sampling; Source; Specific qualifier value; Streptomycin; Structure; Surface; Surface Properties; Symbiosis; Techniques; Testing; Universities; bacterial H antigen; base; capsule; design; feeding; fitness; instrumentation; member; metabolomics; microbial; microbial community; microorganism; mouse model; new technology; novel; programs; rRNA Genes; research study; success; sugar; tool; trait

DESCRIPTION (provided by applicant): The microbial community composition of the human intestine is receiving a lot of attention and now is fairly well characterized. Yet the functional roles of individual microorganisms in the intestinal ecosystem and the dynamic interactions of its community members remain largely uncharacterized, including those interactions that drive competition for resources (i.e., the food web) and those that create conditions favorable for success of the community (e.g., anaerobiosis). Experiments that address these issues cannot be done in humans; they require an animal model that allows testing of the basic ecological principles that underpin the human microbiome. For over a decade, we have used the streptomycin-treated mouse model of intestinal colonization to characterize the functional role of Escherichia coli in the intestine. We learned that different E. coli strains execute different nutritional programs, allowing them to co-colonize the gut. Importantly, we learned that E. coli respires oxygen and thereby lowers the oxygen tension of the cecum, creating conditions that favor growth of the predominantly anaerobic microbial community. Therefore, we hypothesize that E. coli lives in symbiotic relationship with the anaerobes. Since anaerobes are sensitive to oxygen, we predict that the community composition of the intestine depends at least in part on the oxygen scavenging function contributed by E. coli. Since E. coli is unable to hydrolyze complex polysaccharides, which are the primary nutrient source in the gut, and because E. coli can grow only on the degradation products, we predict that anaerobic polysaccharide degradation releases simple sugars that cross-feed E. coli. And, since different E. coli strains execute different nutritional programs in the intestine, we predict that each E. coli strain will interact with distinct subpopulations of the microbial community. Here we outline a Research Plan designed to test these predictions. In Aim 1 we will use high-throughput sequencing of 16S rRNA gene tags and molecular phylogenetic analysis to examine the microbial composition of the streptomycin-treated mouse intestine as it is affected by E. coli colonization. Using isogenic E. coli strains that can and cannot respire oxygen, we will test the prediction that oxygen scavenging in the intestine affects the composition of the anaerobic microbial community. In addition, we will test the prediction that colonization of the intestine with different strains of E. coli, each of which consumes different nutrients in the intestine, will influence the microbial community composition. In Aim 2 we will test the prediction that different E. coli strains physically associate with different members of the microbial community by using 16S analysis of microbes sampled from the intestine by laser capture micro-dissection. Furthermore, we will characterize nutrient flow between E. coli and individual members of the intestinal microbial community in co-cultures. In Aim 3 we wil determine whether surface structures, including O-polysaccharides, flagella, and capsule, target E. coli to specific microhabitats where they could interact with different members of the microbiota. Thus we will characterize the interactions of E. coli with the microbial community in the intestine.

描述（由申请人提供）：人类肠道的微生物群落组成受到广泛关注，并且现在已得到相当好的表征。然而，肠道生态系统中个体微生物的功能作用及其群落成员的动态相互作用在很大程度上仍然没有特征，包括那些推动资源竞争的相互作用（即食物网）和那些为群落成功创造有利条件的相互作用（例如厌氧）。解决这些问题的实验无法在人类身上进行；他们需要一种动物模型来测试支撑人类微生物组的基本生态原理。十多年来，我们一直使用链霉素处理的小鼠肠道定植模型来表征大肠杆菌在肠道中的功能作用。我们了解到，不同的大肠杆菌菌株执行不同的营养程序，使它们能够在肠道中共同定殖。重要的是，我们了解到大肠杆菌呼吸氧气，从而降低盲肠的氧张力，创造有利于主要厌氧微生物群落生长的条件。因此，我们假设大肠杆菌与厌氧菌存在共生关系。由于厌氧菌对氧气敏感，我们预测肠道的群落组成至少部分取决于大肠杆菌贡献的氧清除功能。由于大肠杆菌无法水解复杂的多糖（肠道中的主要营养来源），并且大肠杆菌只能在降解产物上生长，因此我们预测厌氧多糖降解会释放单糖，从而交叉喂养大肠杆菌。而且，由于不同的大肠杆菌菌株在肠道中执行不同的营养程序，我们预测每种大肠杆菌菌株将与微生物群落的不同亚群相互作用。在这里，我们概述了旨在测试这些预测的研究计划。在目标 1 中，我们将使用 16S rRNA 基因标签的高通量测序和分子系统发育分析来检查链霉素处理的小鼠肠道的微生物组成，因为它受到大肠杆菌定植的影响。使用能够和不能呼吸氧气的同基因大肠杆菌菌株，我们将测试肠道中的氧气清除影响厌氧微生物群落组成的预测。此外，我们将测试以下预测：不同菌株的大肠杆菌定植于肠道，每种菌株消耗肠道中不同的营养物质，将影响微生物群落的组成。在目标 2 中，我们将通过激光捕获显微解剖对肠道取样的微生物进行 16S 分析，测试不同的大肠杆菌菌株与微生物群落的不同成员在物理上相关的预测。此外，我们将表征共培养中大肠杆菌和肠道微生物群落个体成员之间的营养流。在目标 3 中，我们将确定表面结构（包括 O-多糖、鞭毛和荚膜）是否将大肠杆菌靶向特定的微生境，在这些微生境中它们可以与微生物群的不同成员相互作用。因此，我们将描述大肠杆菌与肠道微生物群落的相互作用。