古细菌
甲烷厌氧氧化
细胞外
稳定同位素探测
甲烷利用细菌
电子受体
生物
电子转移
微生物种群生物学
甲烷
环境化学
化学
细菌
微生物
生物化学
生态学
光化学
遗传学
作者
Heleen T. Ouboter,Tom Berben,Stefanie Berger,Mike S. M. Jetten,Tom Sleutels,Annemiek ter Heijne,Cornelia U. Welte
标识
DOI:10.3389/fmicb.2022.820989
摘要
Anaerobic methanotrophic (ANME) archaea have recently been reported to be capable of using insoluble extracellular electron acceptors via extracellular electron transfer (EET). In this study, we investigated EET by a microbial community dominated by "Candidatus Methanoperedens" archaea at the anode of a bioelectrochemical system (BES) poised at 0 V vs. standard hydrogen electrode (SHE), in this way measuring current as a direct proxy of EET by this community. After inoculation of the BES, the maximum current density was 274 mA m-2 (stable current up to 39 mA m-2). Concomitant conversion of 13CH4 into 13CO2 demonstrated that current production was methane-dependent, with 38% of the current attributed directly to methane supply. Based on the current production and methane uptake in a closed system, the Coulombic efficiency was about 17%. Polarization curves demonstrated that the current was limited by microbial activity at potentials above 0 V. The metatranscriptome of the inoculum was mined for the expression of c-type cytochromes potentially used for EET, which led to the identification of several multiheme c-type cytochrome-encoding genes among the most abundant transcripts in "Ca. Methanoperedens." Our study provides strong indications of EET in ANME archaea and describes a system in which ANME-mediated EET can be investigated under laboratory conditions, which provides new research opportunities for mechanistic studies and possibly the generation of axenic ANME cultures.
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