Engineering microbiomes and their molecular determinants for production of butyrate and secondary bile acids from resistant starch

项目总结/摘要-项目3 从肠道微生物组产生丁酸盐是由厌氧环境中微生物之间的相互作用引起的。 食物网。鉴定微生物、环境条件和可发酵的产丁酸组合 纤维将成为操纵BMT患者微生物组的策略的基础， 丁酸盐的浓度。假设：1）从可发酵纤维中最大限度地生产SCFA 需要初级纤维降解器、二级发酵器和耗氢发酵器的组合， 微生物2)丁酸盐与总SCFA的比率取决于以下分类学成员： 根据H2浓度、胆汁酸浓度、pH值和细胞周转时间， 环境方法：我们将使用健康人体微生物组的协变分析 队列以鉴定可发酵纤维、物理条件和微生物的产丁酸组合。我们 将通过组装已识别微生物的合成群落并测量 在各种条件下的体外丁酸生产，包括通过 氢营养微生物我们还将从粪便接种物中选择共同进化的产丁酸菌群 使用通过含有可发酵纤维作为主要碳和能量的培养基的多个通道 源头 一旦转运到肠上皮细胞中，丁酸盐可被线粒体氧化。它和可以 还通过过氧化物酶体激活受体（PPARs）刺激线粒体生物合成 位于细胞核上。了解产丁酸微生物组和上皮细胞之间的相互作用 细胞将提供一个丁酸生产之间的时间动态机制的解释， 寄主细胞呼吸假设：结肠中的体外和体内呼吸和线粒体生物合成 上皮细胞将被丁酸盐刺激。方法：呼吸和PPAR激活将 在不同环境条件下暴露于丁酸盐的肠类中测量。对于体内估计值 为了减少呼吸，将六周龄的小鼠置于补充有可发酵的 纤维或易接近的淀粉。每隔12周采集一次GI组织，并进行琥珀酸 将测量脱氢酶和细胞色素氧化酶活性，以量化细胞的能力。 呼吸将在5- 10天治疗的无菌小鼠中跟踪细胞呼吸和粘膜O2浓度。 氨基水杨酸，一种过氧化物酶体增殖物激活物受体激动剂，以区分线粒体生物合成和丁酸 氧化用合成微生物群落定殖的小鼠，用于测试 不同产丁酸能力的微生物组对呼吸的影响。

PROJECT SUMMARY/ABSTRACT – PROJECT 3 The production of butyrate from gut microbiomes results from interactions between microbes in anaerobic food webs. Identifying butyrogenic combinations of microbes, environmental conditions and fermentable fibers will underlie strategies for manipulating the microbiomes in BMT patients to provide therapeutic concentrations of butyrate. Hypotheses: 1) Maximal production of SCFAs from fermentable fibers requires the combination of a primary fiber degraders, secondary fermenters and hydrogen-consuming microbes. 2) The ratio of butyrate to total SCFAs is dependent on the taxonomic membership of communities, which is selected by the concentrations of H2, bile acids, pH and turnover time of the environment. Approaches: We will use covariation analysis of microbiomes from a healthy human cohort to identify butyrogenic combinations of fermentable fibers, physical conditions and microbes. We will test these predictions by assembling synthetic communities of the identified microbes and measuring butyrate production in vitro under various conditions, including the removal of hydrogen by hydrogenotrophic microbes. We will also select co-evolved butyrogenic communities from fecal inocula using multiple passages through media containing fermentable fiber as the primary carbon and energy source. Once transported into an intestinal epithelial cell, butyrate can be oxidized by mitochondria. It and can also stimulate mitochondrial biogenesis through Peroxisome Proliferator-Activated Receptors (PPARs) located on the nucleus. Understanding the interaction between a butyrogenic microbiome and epithelial cells will provide a mechanistic explanation of the temporal dynamics between butyrate production and host cell respiration. Hypothesis: In vitro and in vivo respiration and mitochondrial biogenesis in colonic epithelial cells will be stimulated by butyrate. Approaches: Respiration and PPAR activation will be measured in enteroids exposed to butyrate under varying environmental conditions. For in vivo estimates of respiration, mice at six weeks of age will be placed on a Western diet supplemented with a fermentable fiber(s) or accessible starch. GI tissues will be harvested at intervals up to 12 weeks and succinate dehydrogenase and cytochrome oxidase activities will be measured to quantify the capacity for cellular respiration. Cell respiration and mucosal O2 concentrations will be tracked in germ-free mice treated 5- aminosalicylic acid, a PPAR agonist, to distinguish between mitochondrial biosynthesis and butyrate oxidation. Mice colonized with synthetic communities of microbes to be used to test the impact of microbiomes of different butyrogenic capacity on respiration.