Danchin Antoine, Braham Sherazade
Institute of Cardiometabolism and Nutrition, Hôpital de la Pitié-Salpêtrière, 47 Boulevard de l'Hôpital, 75013, Paris, France.
AMAbiotics SAS, 47 rue de Montmorency, 75003, Paris, France.
Microb Biotechnol. 2017 Jul;10(4):688-701. doi: 10.1111/1751-7915.12722. Epub 2017 Jun 14.
Microbial communities thrive in a number of environments. Exploration of their microbiomes - their global genome - may reveal metabolic features that contribute to the development and welfare of their hosts, or chemical cleansing of environments. Yet we often lack final demonstration of their causal role in features of interest. The reason is that we do not have proper baselines that we could use to monitor how microbiota cope with key metabolites in the hosting environment. Here, focusing on animal gut microbiota, we describe the fate of cobalamins - metabolites of the B12 coenzyme family - that are essential for animals but synthesized only by prokaryotes. Microbiota produce the vitamin used in a variety of animals (and in algae). Coprophagy plays a role in its management. For coprophobic man, preliminary observations suggest that the gut microbial production of vitamin B12 plays only a limited role. By contrast, the vitamin is key for structuring microbiota. This implies that it is freely available in the environment. This can only result from lysis of the microbes that make it. A consequence for biotechnology applications is that, if valuable for their host, B12-producing microbes should be sensitive to bacteriophages and colicins, or make spores.
微生物群落能在多种环境中蓬勃发展。对其微生物组（即它们的整体基因组）的探索，可能会揭示有助于宿主发育和健康，或对环境进行化学净化的代谢特征。然而，我们常常缺乏对它们在感兴趣的特征中因果作用的最终证明。原因在于我们没有合适的基线来监测微生物群如何应对宿主环境中的关键代谢物。在此，我们聚焦于动物肠道微生物群，描述钴胺素（维生素B12辅酶家族的代谢物）的命运，钴胺素对动物至关重要，但仅由原核生物合成。微生物群产生的这种维生素被多种动物（以及藻类）所利用。食粪行为在其管理中发挥作用。对于厌恶食粪的人类来说，初步观察表明肠道微生物产生维生素B12的作用有限。相比之下，这种维生素对构建微生物群至关重要。这意味着它在环境中是可自由获取的。这只能是由产生它的微生物裂解所致。对生物技术应用而言，一个后果是，如果对宿主有价值，产生维生素B12的微生物应该对噬菌体和大肠杆菌素敏感，或者形成孢子。
