The evolution of cooperation within the gut microbiota.
The evolution of cooperation within the gut microbiota.
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DOI：
10.1038/nature17626
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发表时间：
2016-05-12
期刊：
影响因子：
64.8
通讯作者：
Comstock LE
中科院分区：
文献类型：
--
作者：
Rakoff-Nahoum S;Foster KR;Comstock LE
合作表型在许多情况下被认为是微生物群落功能的核心，包括通过群体感应进行沟通、生物被膜形成、抗生素耐药性和发病机制。人体肠道中有一个对健康至关重要的密集而多样的微生物群落，但我们对这个重要生态系统中的合作知之甚少。在这里，我们实验测试类杆菌属内部的进化合作，类杆菌是人类肠道中占主导地位的革兰氏阴性细菌。我们发现，在某些饲料多糖的生长过程中，模型成员thetaiotaomicron杆菌只表现出有限的合作。尽管这种生物在细胞外消化这些多糖，但缺乏这种能力的突变体是竞争对手。相比之下，我们在突出的肠道共生菌卵形杆菌中发现了一种专门的交叉喂养酶系统，它以自身的代价消化多糖，但对其他物种有利。利用体外系统和GnotoBiotic小鼠定植模型，我们发现胞外消化菊粉增加了卵形芽孢杆菌对其他肠道物种(如拟杆菌)的互惠效益，从而提高了其适合度。这是微生物物种之间自然进化合作的罕见例子。我们的研究揭示了哺乳动物肠道微生物区系中合作表型的复杂性和重要性。
Cooperative phenotypes are considered central to the functioning of microbial communities in many contexts, including communication via quorum sensing, biofilm formation, antibiotic resistance, and pathogenesis. The human intestine houses a dense and diverse microbial community critical to health, yet we know little about cooperation within this important ecosystem. Here we experimentally test for evolved cooperation within the Bacteroidales, the dominant Gram-negative bacteria of the human intestine. We show that during growth on certain dietary polysaccharides, the model member Bacteroides thetaiotaomicron exhibits only limited cooperation. Although this organism digests these polysaccharides extracellularly, mutants lacking this ability are outcompeted. In contrast, we discovered a dedicated cross-feeding enzyme system in the prominent gut symbiont Bacteroides ovatus, which digests polysaccharide at a cost to itself but at a benefit to another species. Using in vitro systems and gnotobiotic mouse colonization models, we find that extracellular digestion of inulin increases the fitness of B.ovatus due to reciprocal benefits when it feeds other gut species such as Bacteroides vulgatus. This is a rare example of naturally-evolved cooperation between microbial species. Our study reveals both the complexity and importance of cooperative phenotypes within the mammalian intestinal microbiota.