Abstract：
Methane, the most significant reduced form of carbon on Earth, acts as a crucial fuel and greenhouse gas. Globally, microbial methane sinks encompass both aerobic oxidation of methane (AeOM), conducted by oxygen-utilizing methanotrophs, and anaerobic oxidation of methane (AOM), performed by anaerobic methanotrophs employing various alternative electron acceptors. These electron acceptors involved in AOM include sulfate, nitrate/nitrite, humic substances, and diverse metal oxides. The known anaerobic methanotrophic pathways comprise the internal aerobic oxidation pathway found in NC10 bacteria and the reverse methanogenesis pathway utilized by anaerobic methanotrophic archaea (ANME). Diverse anaerobic methanotrophs can perform AOM independently or in cooperation with symbiotic partners through several extracellular electron transfer (EET) pathways. AOM has been documented in various environments, including seafloor methane seepages, coastal wetlands, freshwater lakes, soils, and even extreme environments like hydrothermal vents. The environmental activities of AOM processes, driven by different electron acceptors, primarily depend on the energy yields, availability of electron acceptors, and environmental adaptability of methanotrophs. It has been suggested that different electron acceptors driving AOM may occur across a wider range of habitats than previously recognized. Additionally, it is proposed that methanotrophs have evolved flexible metabolic strategies to adapt to complex environmental conditions. This review primarily focuses on AOM, driven by different electron acceptors, discussing the associated reaction mechanisms and the habitats where these processes are active. Furthermore, it emphasizes the pivotal role of AOM in mitigating methane emissions.
摘要：
甲烷,地球上最显著的碳还原形式，作为关键的燃料和温室气体。全球范围内,微生物甲烷汇既包括甲烷的好氧氧化(AeOM)，由利用氧气的甲烷营养生物进行，甲烷厌氧氧化（AOM），通过使用各种替代电子受体的厌氧甲烷氧化菌进行。这些参与AOM的电子受体包括硫酸盐，硝酸盐/亚硝酸盐，腐殖质,和多种金属氧化物。已知的厌氧甲烷营养途径包括在NC10细菌中发现的内部需氧氧化途径和厌氧甲烷营养古细菌(ANME)利用的反向产甲烷途径。多种厌氧甲烷氧化菌可以通过几种细胞外电子转移（EET）途径独立或与共生伙伴合作进行AOM。AOM已被记录在各种环境中，包括海底甲烷渗漏，沿海湿地,淡水湖,土壤,甚至像热液喷口这样的极端环境。AOM工艺的环境活动，由不同的电子受体驱动，主要取决于能源产量，电子受体的可用性，和甲烷氧化菌的环境适应性。有人建议，驱动AOM的不同电子受体可能会出现在比以前认识到的更广泛的栖息地中。此外,有人认为甲烷营养菌已经进化出灵活的代谢策略来适应复杂的环境条件。这篇综述主要集中在AOM，由不同的电子受体驱动，讨论相关的反应机制和这些过程活跃的栖息地。此外，它强调了AOM在减少甲烷排放方面的关键作用。
