Genetic Dissection of Nutrient Acquisition in Diverse Akkermansia Strains

肠道微生物区系与人类健康之间的联系已经得到了很好的证实，但其许多居民的特征仍然很差。粘液阿克曼氏菌是一种有益的肠道微生物，与宿主的代谢和免疫健康呈正相关。阿克曼氏菌群通常占肠道微生物区系的1-4%，在某些个体中，可以超过20%。尽管流行，但大多数阿克曼西亚的研究都集中在单一菌株上，影响定居的因素尚不清楚。Akkermansia是已知的唯一在哺乳动物肠道定居的Verrucommicrobia门成员，它占据着一个独特的生态位，在那里它以宿主粘蛋白为食。我和其他人的研究表明，阿克曼西亚的遗传多样性水平惊人，至少有四个不同的系统群，其中大多数仍然没有特征。值得注意的是，许多阿克曼西亚缺乏同化硫酸盐还原的途径，这使得它们依赖于外源硫化物来产生含硫分子，如半胱氨酸。这种降低硫的要求可能会影响微生物与微生物的相互作用，并有可能改变肠道上皮细胞的硫化氢水平。由于硫化氢作为一种具有强大抗炎作用的信号分子，局部硫化氢浓度的变化可能会对宿主和周围微生物区系的生态产生广泛的影响。他说，这项研究计划的长期愿景是使用基因方法来揭示人类肠道微生物区系成员在菌株水平上的分辨率的基本方面。根据这一愿景，本提案中概述的短期目标将揭示阿克马尼亚生物学的基本特征以及影响殖民的特定菌株的相互作用。我们将研究：(1)阿克曼菌毛与宿主糖蛋白之间的相互作用；(2)不同阿克曼属菌株之间碳水化合物利用的遗传机制；(3)特定阿克曼属菌株与产生硫化氢的肠道微生物之间的微生物-微生物相互作用。他说，由于我们独特的资源，我们的实验室处于实现这些目标的绝佳地位。这些包括阿克曼属菌株的集合，阿克曼属转座子突变体的文库，以及我在博士后工作期间开发的操纵阿克曼属的遗传方法的知识，这之前被认为是遗传难题。拟议的研究将提供微生物学、分子生物学、显微镜、高通量遗传筛选、生物信息学和动物模型工作方面的培训。他说，拟议的工作将有助于了解肠道微生物区系中潜在的Keystone成员的生态。更广泛地说，这项研究对于更好地理解肠道微生物群复杂生态系统中的基本宿主-微生物和微生物-微生物相互作用具有重要意义。

The link between the intestinal microbiota and human health is well established, yet many of its inhabitants remain poorly characterized. Akkermansia muciniphila is a beneficial intestinal microbe that is positively correlated with the metabolic and immunologic health of its host. Akkermansia typically represents 1- 4% of the intestinal microbiota, and in some individuals, it can exceed 20%. Despite its prevalence, most Akkermansia research has focused on a single strain, and the factors that influence colonization are unknown.      Akkermansia is the only member of the Phylum Verrucomicrobia known to colonize the mammalian intestine, and it occupies a distinct niche where it forages on host mucins. Work from myself and others indicates that Akkermansia exhibits a striking level of genetic diversity with at least four distinct phylogroups, most of which remain uncharacterized. Notably, many Akkermansia lack pathways for assimilatory sulfate reduction, which renders them dependent on exogenous sulfide to produce sulfur containing molecules such as cysteine. This requirement for reduced sulfur can influence microbe-microbe interactions and has the potential to alter H2S levels at the intestinal epithelium. Because H2S acts as a signalling molecule with potent anti-inflammatory effects, alterations of local H2S concentrations could have broad implications for the host and the ecology of the surrounding microbiota.      The long-term vision for this research program is to use genetic approaches to uncover fundamental aspects of colonization among members of the human intestinal microbiota with strain level resolution. In line with this vision, the short-term objectives outlined in this proposal will reveal basic features of Akkermansia biology and the strain-specific interactions influencing colonization. We will investigate: (1) interactions between Akkermansia pili and host glycoproteins; (2) the genetic mechanisms of carbohydrate utilization among diverse Akkermansia strains; and (3) microbe-microbe interactions between specific Akkermansia strains and H2S producing intestinal microbes.      Our lab is in an excellent position to pursue these aims because of our unique resources. These include a collection of Akkermansia strains, a library of Akkermansia transposon mutants, and knowledge of genetic approaches developed during my postdoctoral work to manipulate Akkermansia, which was previously considered genetically intractable. The proposed research will provide training in microbiology, molecular biology, microscopy, high throughput genetic screens, bioinformatics, and working with animal models.      The proposed work will contribute to understanding the ecology of a potential keystone member of the intestinal microbiota. More broadly, this research has important implications for better understanding basic host-microbe and microbe-microbe interactions in the complex ecosystem of the intestinal microbiome.