AUTHOR=Cai Chen , Ni Gaofeng , Xia Jun , Zhang Xueqin , Zheng Yue , He Bingqing , Marcellin Esteban , Li Weiwei , Pu Jiaoyang , Yuan Zhiguo , Hu Shihu 

TITLE=Response of the Anaerobic Methanotrophic Archaeon Candidatus “Methanoperedens nitroreducens” to the Long-Term Ferrihydrite Amendment

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.799859

DOI=10.3389/fmicb.2022.799859

ISSN=1664-302X

ABSTRACT=<p>Anaerobic methanotrophic (ANME) archaea can drive anaerobic oxidation of methane (AOM) using solid iron or manganese oxides as the electron acceptors, hypothetically <italic>via</italic> direct extracellular electron transfer (EET). This study investigated the response of <italic>Candidatus</italic> “<italic>Methanoperedens nitroreducens</italic> TS” (type strain), an ANME archaeon previously characterized to perform nitrate-dependent AOM, to an Fe(III)-amended condition over a prolonged period. Simultaneous consumption of methane and production of dissolved Fe(II) were observed for more than 500 days in the presence of <italic>Ca.</italic> “<italic>M. nitroreducens</italic> TS,” indicating that this archaeon can carry out Fe(III)-dependent AOM for a long period. <italic>Ca.</italic> “<italic>M. nitroreducens</italic> TS” possesses multiple multiheme <italic>c</italic>-type cytochromes (MHCs), suggesting that it may have the capability to reduce Fe(III) <italic>via</italic> EET. Intriguingly, most of these MHCs are orthologous to those identified in <italic>Candidatus</italic> “<italic>Methanoperedens ferrireducens</italic>,” an Fe(III)-reducing ANME archaeon. In contrast, the population of <italic>Ca.</italic> “<italic>M. nitroreducens</italic> TS” declined and was eventually replaced by <italic>Ca.</italic> “<italic>M. ferrireducens</italic>,” implying niche differentiation between these two ANME archaea in the environment.</p>