In order to persist, successful bacterial inhabitants of the human gut need to adapt to changing nutrient conditions, which are influenced by host diet and a variety of other factors. For members of the Bacteroidetes and several other phyla, this has resulted in the diversification of a variety of enzyme-based systems that equip them to sense and utilize carbohydrate-based nutrients from host, diet, and bacterial origins. In this review, we focus first on human gut Bacteroides and describe recent findings regarding polysaccharide utilization loci (PULs) and the mechanisms of the multiprotein systems that they encode, including their regulation and the expanding diversity of substrates that they target. Next, we highlight previously understudied substrates such as monosaccharides, nucleosides, and Maillard reaction products that can also affect the gut microbiota by feeding symbionts that possess specific systems for their metabolism. Since some pathogens preferentially utilize these nutrients, they may represent nutrient niches competed for by commensals and pathogens. Finally, we address recent work to describe nutrient acquisition mechanisms in other important gut species such as those belonging to the Gram-positive anaerobic phyla Actinobacteria and Firmicutes as well as the Proteobacteria. Because gut bacteria contribute to many aspects of health and disease, we showcase advances in the field of synthetic biology, which seeks to engineer novel, diet-controlled nutrient utilization pathways within gut symbionts to create rationally designed live therapeutics.

中文翻译：

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如果你吃它或分泌它，它们就会生长：人类肠道细菌利用的营养物质清单不断扩大


为了坚持下去，人类肠道中成功的细菌居民需要适应不断变化的营养条件，这些条件受到宿主饮食和各种其他因素的影响。对于拟杆菌门和其他几个门的成员来说，这导致了各种基于酶的系统的多样化，使它们能够感知和利用来自宿主、饮食和细菌来源的基于碳水化合物的营养物质。在这篇综述中，我们首先关注人类肠道拟杆菌，并描述有关多糖利用位点 (PUL) 及其编码的多蛋白系统机制的最新发现，包括它们的调节和它们靶向的底物多样性的扩展。接下来，我们重点介绍以前未充分研究的底物，例如单糖、核苷和美拉德反应产物，这些底物也可以通过喂养具有特定代谢系统的共生体来影响肠道微生物群。由于某些病原体优先利用这些营养物质，因此它们可能代表共生体和病原体争夺的营养位。最后，我们介绍了最近的工作，描述了其他重要肠道物种的营养获取机制，例如属于革兰氏阳性厌氧门放线菌门和厚壁菌门以及变形菌门的物种。由于肠道细菌对健康和疾病的许多方面都有贡献，因此我们展示了合成生物学领域的进展，该领域致力于在肠道共生体中设计新颖的、饮食控制的营养利用途径，以创建合理设计的活体疗法。