生物炭介导的Geobacter-产甲烷菌电子传递过程及稻田产甲烷效应

Biochar land application is an effective way to improve soil quality and enhance carbon sequestration. The influence of biochar on methane emission from paddy soils has become a hotspot in the field of carbon cycling. For a long time, research has been focused on biochar's porosity and its sorptive properties with its conductivity being neglected. Electron transfer between Geobacter-Methanogens is the key factor influencing methane production from paddy soils, and it was found that conductive mineral, such as magnetite, can stimulate methane production. However, to date, little is known about the effect of biochar as conductive media on the electron transfer pattern between Geobacter-Methanogens and whether the electron transfer mediated by biochar will influence methane production in rice field. Therefore, in this project, typical Geobacter and Methanogens will be co-cultured, and laboratory incubation using paddy soils will be carried out. Bioelectrochemical and molecular biological techniques will be employed to investigate the electron transfer process in the "Geobacter-biochar-Methanogens" system so as to reveal the mechanism of how biochar's conductivity influences the eletron transfer process in methanogenesis and to evaluate the influence of interspecies electron trasfer mediated by biochar on methanogenesis in paddy soils. It is expected that results from this project will provide theoretical foundation for carbon cycling in agricultural soils and provide technical support for mitigation of methane emission from paddy soils.

生物炭土地利用是改善土壤质量、固碳增汇的有效途径。生物炭对稻田产甲烷过程的影响是当前土壤碳循环的研究热点。长期以来，生物炭对稻田产甲烷影响多集中在生物炭的多孔性和吸附性等属性上，其导电性则少受关注。Geobacter-产甲烷菌间的电子传递是影响稻田产甲烷的关键，前人研究发现导电矿物（如磁铁矿）可加速产甲烷过程。然而，生物炭作为导电介质，介导的种间电子传递及对稻田产甲烷的影响却未见报道。本项目拟以水稻土中典型Geobacter和产甲烷菌为代表进行互营共培养，并结合室内水稻土培育实验，借助生物电化学与现代分子生物学手段，探讨"Geobacter-生物炭-产甲烷菌"共存体系中的电子传递过程，揭示生物炭导电性对产甲烷电子转移过程的影响机制。探明生物炭介导的种间电子传递途径及其对稻田产甲烷过程的影响效应，为发展完善和合理管理农田碳循环过程提供理论依据，为稻田温室气体减排提供技术支撑。

生物炭对稻田产甲烷过程的影响是土壤碳循环的研究热点,本项目以生物炭的导电性为研究切入点，围绕胞外呼吸菌-导电生物炭-产甲烷菌交互体系，借助生物电化学和分子生物学手段，研究了导电生物炭对胞外电子传递途径的影响及其环境效应。主要成果包括：（1）以G. sulfurreducens/M. barkeri纯菌共培养体系为研究对象，考察了生物炭介导的Geobacter-Methanosarcina互营产甲烷过程，阐明了生物炭导电性与产甲烷过程的响应关系及种间电子传递途径。（2）以G. sulfurreducens为研究对象，考察导电生物炭作为微生物胞外电子受体的可能性，初步证实了生物炭上的醌基等基团是接收胞外电子的主要成分；（3）以G. sulfurreducens为研究对象，探讨了导电生物炭作为固体电子穿梭体对五氯酚厌氧降解的促进效应，阐明了生物炭介导的五氯酚降解途径及胞外电子传递机制。本项目初步揭示了生物炭介导的胞外电子传递过程，及其对产甲烷过程和有机物厌氧降解的微生物机制，为深入理解导电物质介导的胞外电子传递机制及其影响的土壤生物地球化学过程提供科学依据，为研发温室气体调控策略和有机物厌氧降解技术提供了技术支撑。项目共发表SCI论文4篇；培养硕士研究生1名。