Yu Zheng, Chistoserdova Ludmila
Department of Chemical Engineering, University of Washington, Seattle, Washington 98195.
Department of Chemical Engineering, University of Washington, Seattle, Washington 98195
J Bacteriol. 2017 Jun 19;199(22):e00328-17. doi: 10.1128/JB.00328-17.
Metabolism of methane is an important part of biogeochemical cycling of carbon. Methane is also a major contributor to climate change. A specialized group of microbes that consume methane, the methanotrophs, represent a natural filter preventing an even faster accumulation of methane in the atmosphere. Methanotrophy can proceed via both anaerobic and aerobic modes. The anaerobic methanotrophs, represented by both archaea and bacteria, all appear to be engaged in syntrophic interdependencies with other species, to overcome the energetic barriers of methane metabolism in the absence of oxygen. In contrast, aerobic methanotrophy can be carried out by pure cultures of bacteria. Nevertheless, a concept of communal function in aerobic methane oxidation has been gaining momentum, based on data from natural cooccurrence of specific functional guilds, and based on results from laboratory manipulations. The mechanistic details are still sparse on how and why the methanotrophs share their carbon with other species, and whether and what they gain in return. In this minireview we highlight recent studies that led to this new concept of community function in aerobic methane oxidation. We first describe the stable isotope probing experiments employing heavy carbon-labeled methane, tracing methane carbon consumption. We then follow up with analysis of data from microcosm community dynamics. We further discuss the role of a synthetic community approach in unraveling the principles of carbon flow and species cooperation in methane consumption. Finally, we touch on the role of lanthanides, which are rare Earth elements, previously thought to be biologically inert, in bacterial metabolism of methane.
甲烷代谢是碳生物地球化学循环的重要组成部分。甲烷也是气候变化的主要促成因素。一类专门消耗甲烷的微生物，即甲烷氧化菌，是一种天然过滤器，可防止甲烷在大气中更快地积累。甲烷氧化可通过厌氧和好氧两种方式进行。以古菌和细菌为代表的厌氧甲烷氧化菌似乎都与其他物种存在共生关系，以克服在无氧条件下甲烷代谢的能量障碍。相比之下，好氧甲烷氧化可以由细菌的纯培养物进行。然而，基于特定功能群落自然共存的数据以及实验室操作的结果，好氧甲烷氧化中的群落功能概念越来越受到关注。关于甲烷氧化菌如何以及为何与其他物种共享碳，以及它们是否以及得到了什么回报，其机制细节仍然很少。在这篇小型综述中，我们重点介绍了导致好氧甲烷氧化中群落功能这一新概念的最新研究。我们首先描述了使用重碳标记甲烷的稳定同位素探测实验，追踪甲烷碳的消耗。然后我们接着分析微观群落动态的数据。我们进一步讨论了合成群落方法在揭示甲烷消耗中碳流和物种合作原理方面的作用。最后，我们探讨了镧系元素（以前被认为是生物惰性的稀土元素）在细菌甲烷代谢中的作用。
