微生物催化CO2电甲烷化及胞外电子传输与诱导调控的分子机制

微生物电解池以电活性功能菌为催化剂，催化还原CO2合成甲烷，是环境、能源、生物等领域研究热点。但交换膜污染、质子迁移难、CO2气液传质慢等难题，严重制约电甲烷化性能; 且胞外电子传输机制亟待完善。本项目拟构建连续式CO2电甲烷化反应体系和“生物气膜面切向循环扫流微单元”，原位剥离膜面胶体/大分子聚合物，强化质子跨膜传输，加速CO2气液传质，通过解析膜-污键合/脱析动态、“气-液-菌”物质传递及碳流向与转化机制，提出最佳膜污染原位防控与CO2电甲烷化策略；追踪表征生物膜负载、电催化活性及群落动态演替，推演极面-功能菌电子传输行为和复杂菌种间协同/竞争效应，识别功能菌执行胞外电子传输的主控基因及色素类型，从分子和基因水平揭示CO2电甲烷化动力源的激发原理与调控机制。本项目预期将为构建稳定的人工原位CO2固定与碳中和技术，完善电甲烷化及胞外电子传输机制，推动规模化碳减排与增值回用提供技术储备。

Microbial electrolysis cell (MEC) represents a newly emerging CO2 utilization strategy that can bioelectrochemically reduce CO2 and simultaneously electrosynthesize biomethane by using electrochemically active bacteria colonizing on the biocathode as biocatalysts. However, electrochemical reduction of CO2 is hindered by rapid membrane fouling, slow proton and CO2 mass transfer and poor process stability; more importantly, the principle mechanisms in extracellular electron transport are yet unclear. Therefore, the specific objective of this research is to develop a continuous and robust electromethanogenesis process for CO2 conversion and methane production. For those purposes, a series of two-chamber MEC reactors equipped with a tangential biogas recirculation unit along the membrane surface within cathodic chamber will be designed and run in parallel with gaseous CO2 as the sole carbon source to control the membrane fouling and enhance proton transport and CO2 dissolution. The formation and desorption dynamics of foulants on the membrane, and the responsible mechanisms for mass transfer and carbon conversion among gas-liquid-cells during the long-term operation will be explored to optimize the operational parameters for maximizing CO2 electroduction and methane productivity. Meanwhile, the changes in viabilities, microbial community, interspecific ecological niche and bioelectrocatalytic activities of the developed cathodic biofilms, the electron transport and exchange behaviors occurring at the microbe–electrode interface over time as well as the key genes governing CO2 bioconversion and direct electron uptake will be investigated to in-depth recognize thermodynamic working principles and bioelectrocatalytic routes for the regulated and stimulated bioelectroreduction process, and to enrich the theory system of electromethanogenesis and extracellular electron transfer. The current work can provide the scientific basis for developing a highly efficient and robust process for real wasted CO2 conversion and reuse, alleviating the dependence on fossil fuels and ensuring the energy security.