Anaerobic oxidation of methane (AOM) plays a crucial role in controlling the flux of methane from anoxic environments. Sulfate-, nitrite-, nitrate-, and iron-dependent methane oxidation processes have been considered to be responsible for the AOM activities in anoxic niches. We report that nitrate-reducing AOM microorganisms, enriched in a membrane biofilm bioreactor, are able to couple selenate reduction to AOM. According to ion chromatography, X-ray photoelectron spectroscopy, and long-term bioreactor performance, we reveal that soluble selenate was reduced to nanoparticle elemental selenium. High-throughput 16S rRNA gene sequencing indicates that Candidatus Methanoperedens and Candidatus Methylomirabilis remained the only known methane-oxidizing microorganisms after nitrate was switched to selenate, suggesting that these organisms could couple anaerobic methane oxidation to selenate reduction. Our findings suggest a possible link between the biogeochemical selenium and methane cycles.

中文翻译：

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脱氮厌氧甲烷氧化生物膜驱动的微生物硒酸盐还原

甲烷的厌氧氧化（AOM）在控制来自缺氧环境的甲烷流量方面起着至关重要的作用。硫酸盐，亚硝酸盐，硝酸盐和铁依赖的甲烷氧化过程被认为是缺氧环境中AOM活性的原因。我们报告说，减少硝酸盐的AOM微生物，在膜生物膜生物反应器中富集，能够将硒酸盐还原耦合到AOM。根据离子色谱，X射线光电子能谱和长期的生物反应器性能，我们发现可溶性硒酸盐被还原为纳米元素硒。高通量16S rRNA基因测序表明，暂定Methanoperedens和暂定硝酸盐转换为硒酸盐后，甲烷rabi菌仍然是唯一已知的甲烷氧化微生物，这表明这些生物体可以将厌氧甲烷氧化与硒酸盐还原反应耦合。我们的发现表明，生物地球化学硒与甲烷循环之间可能存在联系。