Active pathways of anaerobic methane oxidation across contrasting riverbeds

• DOI: 10.1038/s41396-018-0302-y
• Publication Date: 2018-10-30T09:23:10Z
• Authors: Li-dong Shen; Liao Ouyang; Yizhu Zhu; Mark Trimmer
• Keywords: Candidatus; Deltaproteobacteria; Sulfate-Reducing Bacteria

Abstract Anaerobic oxidation of methane (AOM) reduces emissions from marine ecosystems but we know little about AOM in rivers, whose role the global carbon cycle is increasingly recognized. We measured potentials driven by different electron acceptors, including nitrite, nitrate, sulfate, and ferric iron, identified microorganisms involved across contrasting riverbeds. activity was confined to more reduced, sandy riverbeds, whereas no less gravel riverbeds where there were few anaerobic methanotrophs. Nitrite-dependent nitrate-dependent occurred all with maximum rates 61.0 20.0 nmol CO2 g−1 (dry sediment) d−1, respectively, while sulfate-dependent iron-dependent only concentration highest diversity pathways greatest. Diverse Candidatus Methylomirabilis oxyfera (M. oxyfera)-like bacteria Methanoperedens nitroreducens nitroreducens)-like archaea detected (16S rRNA gene abundance 9.3 × 105 1.5 107 2.1 104 2.5 copies dry sediment, respectively) other known Further, found M. oxyfera-like nitroreducens-like be actively nitrite- nitrate/ferric AOM, respectively. Hence, demonstrate multiple relation methane, though activities are dominant.