生物电子介导的短链脂肪酸互营氧化产甲烷机理研究

Interspecies electron transfer, which establishs the basis of syntrophic methanogenesis, is facilitated by bioelectrons through high conductive mineral Fe3O4, showing a fast methane production. However, mechanisms for interspecies electron transfer of syntrophic methanogenesis mediated by bioelectrons is less clear due to complex environmental conditions. Here, we use Fe3O4 as conduits of electrons to enrich syntrophic cocultures from anaerobic digested sludge by using cascade acclimation. Various techniques, such as electrochemistry, metatranscriptomics, stable isotope probing, 454 pyrosequencing platform, FISH, LC/GC-MS, are combined to explore the structure and function of microbial commuity, mechanisms of direct interspecies electron transfer, and methanogenic pathway for selected syntrophic cocultures in respond to different substrate, and also to further clarify the relationship between direct interspecies electron transfer and syntrophic methanogenesis, thus establishing the basis of demonstrating the the mechanisms for bioelectron-mediated syntrophic methanogenesis. These studies will provide fundamental knowledge for design of a innovative biomethane production.

种间电子传递是微生物建立互营合作生成甲烷的基础，具有高导电性的Fe3O4可作为电子导线促进细菌和甲烷菌之间的电子传递，进而加速甲烷的生成。然而，由于环境条件的复杂性，生物电子介导的互营产甲烷核心--种间电子传递机理尚未明晰。本项目拟以厌氧消化污泥为研究体系，在引入Fe3O4的前提下，采用级联驯化策略，定向构建生物电子介导的互营产甲烷共培养体系。借助多种技术手段，包括电化学、转录组学、稳定性同位素示踪、454焦磷酸测序、FISH、LC/GC-MS等技术，研究所筛选的共培养体系在不同底物响应下的微生物群落的结构与功能、种间电子直接传递机理和产甲烷路径，揭示互营共培养体系的种间电子直接传递与产甲烷过程的偶联关系，从而为阐明生物电子介导的互营产甲烷机理奠定基础。这些研究将为设计创新性的甲烷生产过程提供理论和实践依据。

Fe3O4可以促进有机物快速转化成为甲烷。本项目通过从厌氧消化污泥和稻田土添加Fe3O4，成功富集出4种互营产甲烷共培养体系。并对其中3种，从电子供体降解特性、甲烷生成动力学、菌群结构与功能、产甲烷路径等方面详细研究了共培养体系的特征，揭示了共培养体系菌群结构、Fe（III）还原与甲烷生成特点之间的关系。阐明Fe3O4介导的甲烷快速生成机理，即：Fe3O4以作为电子受体的方式，促进了乙醇、丙酸等小分子有机物快速转化成为甲烷。同时阐明铁还原菌与氢气营养型甲烷菌经种间H2转移建立了互营共生关系。选育的共培养体系可以成功用于以复杂有机物为给料的厌氧消化产甲烷过程，切实提高了甲烷生成速率和产量，为提高沼气工程运行效率和产甲烷性能奠定了坚实的基础。研究成果在Bioresource Technology, RSC Advance, Scientific Reports等期刊发表SCI论文7篇，获得授权发明专利1项。