Aix-Marseille University, Univ Toulon, CNRS, IRD, M.I.O. UM 110, Mediterranean Institute of Oceanography, Marseille, France; Institute of Ecology and Biodiversity IEB, Faculty of Sciences, Universidad de Chile, Santiago, Chile; Escuela de Ingeniería Bioquímica, Pontificia Universidad de Valparaiso, Av Brasil 2085, Valparaiso, Chile.
Biotechnology and Bioengineering Department, Center for Research and Advanced Studies (Cinvestav), Mexico City, Mexico.
Sci Total Environ. 2020 Sep 20;736:139588. doi: 10.1016/j.scitotenv.2020.139588. Epub 2020 May 25.
Arctic lakes emit methane (CH) to the atmosphere. The magnitude of this flux could increase with permafrost thaw but might also be mitigated by microbial CH oxidation. Methane oxidation in oxic water has been extensively studied, while the contribution of anaerobic oxidation of methane (AOM) to CH mitigation is not fully understood. We have investigated four Northern Siberian stratified lakes in an area of discontinuous permafrost nearby Igarka, Russia. Analyses of CH concentrations in the water column demonstrated that 60 to 100% of upward diffusing CH was oxidized in the anoxic layers of the four lakes. A combination of pmoA and mcrA gene qPCR and 16S rRNA gene metabarcoding showed that the same taxa, all within Methylomonadaceae and including the predominant genus Methylobacter as well as Crenothrix, could be the major methane-oxidizing bacteria (MOB) in the anoxic water of the four lakes. Correlation between Methylomonadaceae and OTUs within Methylotenera, Geothrix and Geobacter genera indicated that AOM might occur in an interaction between MOB, denitrifiers and iron-cycling partners. We conclude that MOB within Methylomonadaceae could have a crucial impact on CH cycling in these Siberian Arctic lakes by mitigating the majority of produced CH before it leaves the anoxic zone. This finding emphasizes the importance of AOM by Methylomonadaceae and extends our knowledge about CH cycle in lakes, a crucial component of the global CH cycle.
北极湖泊向大气中排放甲烷（CH）。这种通量的大小可能会随着永冻土的融化而增加，但也可能会被微生物 CH 氧化所缓解。好氧水中的甲烷氧化已经得到了广泛的研究，而厌氧甲烷氧化（AOM）对 CH 缓解的贡献尚不完全清楚。我们研究了俄罗斯伊加尔卡附近一个不连续永冻区的四个北西伯利亚分层湖泊。水柱中 CH 浓度的分析表明，四个湖泊的缺氧层中向上扩散的 CH 有 60%到 100%被氧化。pmoA 和 mcrA 基因 qPCR 以及 16S rRNA 基因宏条形码分析表明，同一类群的细菌，都属于甲基单胞菌科，包括主要属甲基杆菌和 Crenothrix，可能是四个湖泊缺氧水中的主要甲烷氧化细菌（MOB）。甲基单胞菌科与 Methylotenera、Geothrix 和 Geobacter 属内的 OTUs 之间的相关性表明，AOM 可能发生在 MOB、反硝化菌和铁循环伙伴之间的相互作用中。我们的结论是，甲基单胞菌科中的 MOB 通过在缺氧区将产生的 CH 大部分氧化之前，对这些西伯利亚北极湖泊中的 CH 循环可能产生至关重要的影响。这一发现强调了甲基单胞菌科的 AOM 的重要性，并扩展了我们对湖泊 CH 循环的认识，湖泊是全球 CH 循环的关键组成部分。
