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=

Anaerobic methanotrophic (ANME) archaea can drive anaerobic oxidation of methane (AOM) using solid iron or manganese oxides as the electron acceptors, hypothetically via direct extracellular electron transfer (EET). This study investigated the response of CandidatusMethanoperedens nitroreducens 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 Ca.M. nitroreducens TS,” indicating that this archaeon can carry out Fe(III)-dependent AOM for a long period. Ca.M. nitroreducens TS” possesses multiple multiheme c-type cytochromes (MHCs), suggesting that it may have the capability to reduce Fe(III) via EET. Intriguingly, most of these MHCs are orthologous to those identified in CandidatusMethanoperedens ferrireducens,” an Fe(III)-reducing ANME archaeon. In contrast, the population of Ca.M. nitroreducens TS” declined and was eventually replaced by Ca.M. ferrireducens,” implying niche differentiation between these two ANME archaea in the environment.