人体中最多的成分是什么?细胞?基因?都不对,是微生物!它们的数量与人体细胞的比例达到10∶1。仅在我们人体肠道中,就含有超过100万亿个细菌,这些细菌有助于人体消化食物,产生维生素以预防食物中细菌所诱发的疾病,同时刺激免疫系统。肠壁中的所有这些细菌与身体的其余部分分离,肠壁作为一道选择性屏障发挥作用,只允许有用的物质通过,并在体内被吸收。随着研究深入,科学家发现肠道微生物在许多慢性疾病和症状中,如炎症、肥胖等也起了关键作用。 The evolution of cooperation within the gut microbiota Gang Zhou, Shu Meng, Yanhui Li, Yohannes T. Ghebre, John P. Cooke Cooperative phenotypes are considered central to the functioning of microbial communities in many contexts, including communication via quorum sensing, biofilm formation, antibiotic resistance, and pathogenesis1, 2, 3, 4, 5. The human intestine houses a dense and diverse microbial community critical to health1, 2, 4, 5, 6, 7, 8, 9, yet we know little about cooperation within this important ecosystem. Here we test experimentally 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 owing 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. 转化医学:生物谷旗下转化医学专业平台 |
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