Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, USA.
Department of Biological Science, University of Southern California, Los Angeles, California 90089, USA.
Nat Commun. 2014 Oct 14;5:5094. doi: 10.1038/ncomms6094.
The atmospheric flux of methane from the oceans is largely mitigated through microbially mediated sulphate-coupled methane oxidation, resulting in the precipitation of authigenic carbonates. Deep-sea carbonates are common around active and palaeo-methane seepage, and have primarily been viewed as passive recorders of methane oxidation; their role as active and unique microbial habitats capable of continued methane consumption has not been examined. Here we show that seep-associated carbonates harbour active microbial communities, serving as dynamic methane sinks. Microbial aggregate abundance within the carbonate interior exceeds that of seep sediments, and molecular diversity surveys reveal methanotrophic communities within protolithic nodules and well-lithified carbonate pavements. Aggregations of microbial cells within the carbonate matrix actively oxidize methane as indicated by stable isotope FISH-nanoSIMS experiments and (14)CH4 radiotracer rate measurements. Carbonate-hosted methanotrophy extends the known ecological niche of these important methane consumers and represents a previously unrecognized methane sink that warrants consideration in global methane budgets.
海洋中甲烷的大气通量在很大程度上通过微生物介导的硫酸盐耦合甲烷氧化来缓解，导致自生碳酸盐的沉淀。深海碳酸盐在活动的和古甲烷渗漏处很常见，主要被视为甲烷氧化的被动记录者; 它们作为能够持续消耗甲烷的活跃和独特的微生物栖息地的作用尚未得到检验。在这里，我们表明，与渗漏有关的碳酸盐中蕴藏着活跃的微生物群落，是动态的甲烷汇。碳酸盐内部的微生物聚集体丰度超过了渗漏沉积物的丰度，分子多样性调查显示在原质结核和高度石化的碳酸盐铺层中有甲烷营养微生物群落。碳酸盐基质中微生物细胞的聚集物通过稳定同位素 FISH-nanoSIMS 实验和 (14)CH4 放射性示踪剂速率测量表明它们能够积极地氧化甲烷。碳酸盐中存在的甲烷氧化作用扩展了这些重要的甲烷消费者的已知生态位，代表了一个以前未被认识到的甲烷汇，值得在全球甲烷预算中加以考虑。
