Multi-heme cytochrome-mediated extracellular electron transfer by the anaerobic methanotroph 'Candidatus Methanoperedens nitroreducens'

作者：Zhang, Xueqin; Joyce, Georgina H.; Leu, Andy O.; Zhao, Jing; Rabiee, Hesamoddin; Virdis, Bernardino; Tyson, Gene W.; Yuan, Zhiguo; Mcilroy, Simon J.; Hu, Shihu^*

来源：Nature Communications, 2023, 14(1): 6118.

DOI：10.1038/s41467-023-41847-w

Anaerobic methanotrophic archaea (ANME) carry out anaerobic oxidation of methane, thus playing a crucial role in the methane cycle. Previous genomic evidence indicates that multi-heme c-type cytochromes (MHCs) may facilitate the extracellular electron transfer (EET) from ANME to different electron sinks. Here, we provide experimental evidence supporting cytochrome-mediated EET for the reduction of metals and electrodes by 'Candidatus Methanoperedens nitroreducens', an ANME acclimated to nitrate reduction. Ferrous iron-targeted fluorescent assays, metatranscriptomics, and single-cell imaging suggest that 'Ca. M. nitroreducens' uses surface-localized redox-active cytochromes for metal reduction. Electrochemical and Raman spectroscopic analyses also support the involvement of c-type cytochrome-mediated EET for electrode reduction. Furthermore, several genes encoding menaquinone cytochrome type-c oxidoreductases and extracellular MHCs are differentially expressed when different electron acceptors are used.