厌氧甲烷氧化古菌的电化学特性及胞外电子传递机制

厌氧甲烷氧化(AOM)是厌氧环境中甲烷消耗的主要途径。其中，古菌/细菌间的互营代谢（即古菌呼出电子/细菌吸入电子的过程）是AOM的核心科学问题。然而，目前对于AOM的研究主要集中在古菌/细菌聚集体，解耦联状态下单独研究古菌的甲烷氧化机制的报道还非常少见。在现有AOM种间胞外电子传递理论的基础上，本项目将“AOM古菌与Fe(III)/电极还原”联系起来，提出AOM古菌外膜细胞色素蛋白直接介导的胞外电子传递假说。以AOM富集培养物为研究对象，以铁氧化物和固体电极为电子受体，甲烷为唯一电子供体，采用电化学原位光谱、扫描电化学显微镜等技术解析AOM古菌胞外电子传递能力和分子机制，从胞外呼吸角度系统研究AOM古菌的电化学活性和胞外电子传递效率，揭示细胞色素蛋白介导的古菌胞外电子传递机制，为理解厌氧环境中甲烷氧化机理及其与土壤矿物还原的关系提供新的线索，为削减温室气体排放提供理论依据。

Anaerobic oxidation of methane (AOM) driven by archaea acts as a main methane sink in anaerobic environments. The interspecies electron transfer between archaea and the partner bacteria is a key scientific issue for understanding the process and mechanism of AOM. However, most previous studies are mainly focused on the syntrophic and metabolic interactions of microbial consortia, few investigations have been carried out to explore the mechanisms of AOM by archaea alone under decoupled conditions. Based on previous observations that direct electron transfer between archaea and the partner bacteria is a principal mechanism of AOM, we link the processes of AOM and extracellular electron transfer (EET) and reduction of solid electron acceptors, and propose a hypothesis that outer membrane cytochrome proteins of archaea play a dominant role in mediating EET of AOM. This project aims to investigate systematically the EET property and electrochemical activity of AOM archaea enrichment culture. Using Fe(III) oxides and solid electrodes as electron acceptors and methane as an electron donor, the efficiency and pathway of EET by AOM archaea will be elucidated via many techniques including electrochemical in situ spectroscopy, scanning electrochemical microscopy. The role of cytochrome proteins and the molecular mechanisms of EET in the AOM process will be illuminated. Results of the project will provide new insights into the AOM principle and its relationship with reductive transformation of soil minerals, and provide a theoretical basis for controlling the greenhouse gas emission.