Eutrophic lakes are major contributors to global aquatic methane emissions. Methanotrophy, performed by methane oxidizing bacteria, results in the production of biomass, fermentation products and/or CO₂, making methane‐derived carbon available to non‐methanotrophic organisms. Methanotrophs can co‐occur with methylotrophs which are expected to consume methane‐derived carbon. However, it is unknown if this interaction requires cell‐to‐cell contact, whether physicochemical factors affect this interaction, and what role this interaction may play in ecosystems and biogeochemical cycling in lakes. Here, we performed incubations of an enrichment culture obtained from a eutrophic lake with ¹³C‐labeled methane, revealing the transfer of methane‐derived carbon from the methanotroph Methylobacter sp. to a methylotroph of the genus Methylotenera. These microorganisms occurred both in mixed clusters and as single cells, indicating that their interaction does not require physical cell contact. In addition, the carbon transfer between the partners is dependent on the presence of nitrate, which is potentially used by Methylotenera sp. and in turn may affect the methane oxidation rate of Methylobacter sp. This interaction, and its dependence on nitrate, may have important implications for the carbon cycle in eutrophic lakes worldwide.

中文翻译：

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硝酸盐促进甲烷氧化菌甲基杆菌属中甲烷衍生的碳的转移。甲基营养菌Methylotenera sp。在富营养化的湖水中

富营养化湖泊是导致全球水生甲烷排放的主要因素。甲烷氧化作用是由甲烷氧化细菌完成的，导致产生生物质，发酵产物和/或CO ₂，使甲烷来源的碳可用于非甲烷营养生物。甲烷营养菌可能与甲基营养菌同时出现，而甲基营养菌会消耗甲烷产生的碳。但是，尚不清楚这种相互作用是否需要细胞间的接触，理化因素是否会影响这种相互作用，以及这种相互作用在湖泊的生态系统和生物地球化学循环中可能起什么作用。在这里，我们对富营养化湖中富含¹³ C标记的甲烷的培养物进行了温育，揭示了甲烷从甲烷中转移出碳甲基杆菌属 属的甲基营养Methylotenera。这些微生物既以混合簇形式出现，也以单细胞形式出现，表明它们的相互作用不需要物理细胞接触。另外，伙伴之间的碳转移取决于硝酸盐的存在，而硝酸盐可能被甲基化菌利用。进而可能会影响甲基杆菌属（Methylobacter sp。）的甲烷氧化速率。这种相互作用及其对硝酸盐的依赖性可能对全世界富营养化湖泊的碳循环具有重要意义。