Yu Hang, Xu Shuai, Jangir Yamini, Wegener Gunter, Orphan Victoria J, El-Naggar Mohamed Y
College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089, USA.
Sci Adv. 2025 Aug 22;11(34):eadw4289. doi: 10.1126/sciadv.adw4289.
Anaerobic methanotrophic archaea (ANME) and sulfate-reducing bacteria (SRB) form syntrophic partnerships in marine sediments to consume greenhouse gas methane. While direct interspecies electron transport is proposed to enable ANME/SRB symbiosis, its electrochemical properties remain uncharacterized. Here, using sediment-free enrichment cultures, we measured the electron transport capabilities of marine consortia under physiological conditions. Diverse ANME/SRB consortia exhibited high dry conductance close to electrogenic biofilms. This conductance diminished upon exposure to heat or oxygen but was preserved following paraformaldehyde fixation, indicating a biomolecular origin for this electric charge transfer. Cyclic voltammetry revealed redox activity centered at 28 ± 11, 94 ± 6, and 24 ± 7 millivolts for ANME-1/, ANME-2a/Seep-SRB1, and ANME-2a+2c/Seep-SRB1+2 consortia, respectively. Generator-collector measurements further demonstrated that these redox components facilitate electron transport over micrometer-scale distances, sufficient to link archaeal and bacterial partners. Collectively, our results establish that marine ANME/SRB symbiosis uses redox conduction, consistent with multiheme cytochrome , for direct interspecies electron transport.
厌氧甲烷氧化古菌（ANME）和硫酸盐还原细菌（SRB）在海洋沉积物中形成互营共生关系以消耗温室气体甲烷。虽然有人提出种间直接电子传递能够实现ANME/SRB共生，但这种传递的电化学性质仍未得到表征。在此，我们使用无沉积物富集培养物，在生理条件下测量了海洋菌群的电子传递能力。不同的ANME/SRB菌群表现出接近产电生物膜的高干电导率。这种电导率在受热或接触氧气后会降低，但在多聚甲醛固定后仍能保持，这表明这种电荷转移起源于生物分子。循环伏安法显示，ANME-1/、ANME-2a/Seep-SRB1和ANME-2a+2c/Seep-SRB1+2菌群的氧化还原活性分别集中在28±11、94±6和24±7毫伏。发生器-收集器测量进一步证明，这些氧化还原成分促进了微米级距离上的电子传递，足以连接古菌和细菌伙伴。总的来说，我们的结果表明，海洋ANME/SRB共生利用氧化还原传导，这与多血红素细胞色素一致，用于种间直接电子传递。
