Anaerobic methane oxidation linked to Fe(III) reduction in a Candidatus Methanoperedens‐enriched consortium from the cold Zoige wetland at Tibetan Plateau

Abstract

Summary Anaerobic oxidation of methane (AOM) is a microbial process degrading ample methane in anoxic environments, and Ca. Methanoperedens mediated nitrate‐ or metal‐reduction linked AOM is believed important in freshwater systems. This work, via 16S rRNA gene diversity survey and 16S rRNA quantification, found abundant Ca. Methanoperedens along with iron in the cold Zoige wetland at Tibetan Plateau. The wetland soil microcosm performed Fe(III) reduction, rather than nitrate‐ nor sulphate‐reduction, coupled methane oxidation (3.87 μmol d−1) with 32.33 μmol Fe(II) accumulation per day at 18°C, but not at 30°C. A metagenome‐assembled genome (MAG) recovered from the microcosm exhibits ~74% average nucleotide identity with the reported Ca. Methanoperedens spp. that perform Fe(III) reduction linked AOM, thus a novel species Ca. Methanoperedens psychrophilus was proposed. Ca. M. psychrophilus contains the whole suite of CO2 reductive methanogenic genes presumably involving in AOM via a reverse direction, and comparative genome analysis revealed its unique gene categories: the multi‐heme clusters (MHCs) cytochromes, the S‐layer proteins highly homologous to those recovered from lower temperature environments and type IV pili, those could confer Ca. M. psychrophilus of cold adaptability. Therefore, this work reports the first methanotroph implementing AOM in an alpine wetland.

Microbial sensitivity to temperature and sulfate deposition modulates greenhouse gas emissions from peat soils

“…Anaerobic oxidation of methane is another critical CH 4 sink in peatlands, but the biogeochemistry and microbial ecology behind these processes are not well understood (Chen et al, 2022). Fe (III) and sulfate are potential electron acceptors for AOM; however, it is unclear to what extent low sulfate concentrations constrain AOM‐sulfate reduction coupling or whether Fe (III) reduction drives AOM directly (van Grinsven et al, 2020).…”

“…Anaerobic oxidation of methane is another critical CH 4 sink in peatlands, but the biogeochemistry and microbial ecology behind these processes are not well understood (Chen et al, 2022) The couplings between various sulfate concentrations, sulfate reduction, and methanogenesis rates in peatlands have not been thoroughly examined. Therefore, the threshold by which SRBs outcompete and/or coexist with methanogens is yet to be fully elucidated.…”

Metal-Driven Anaerobic Oxidation of Methane as an Important Methane Sink in Methanic Cold Seep Sediments

“…In iron-reducer Geobacter sulfurreducens , the process of EET is carried out via MHCs during metal reduction ( 27 , 48 ). For ANME-2d from freshwater Fe-AOM enrichment, a set of MHCs for extracellular dissimilatory Fe(III) reduction were highly expressed ( 12 , 49 , 50 ). Here, all analyzed ANME genomes were found to contain the genes encoding several c-type and periplasmic cytochromes (see Table S9 in the supplemental material).…”

Metal-driven anaerobic oxidation of methane as an important methane sink in methanic cold seep sediments

“…In iron-reducer Geobacter sulfurreducens , the process of EET is carried out via MHCs during metal reduction 44 26 . For ANME-2d from freshwater Fe-AOM enrichment, a set of MHCs for extracellular dissimilatory Fe(III) reduction were highly expressed 12, 45, 46 . Here, all analyzed ANME genomes were found to contain the genes encoding several c-type and periplasmic cytochromes ( Table S8 ).…”