膜囊泡介导Geobacter sulfurreducens胞外电子传递过程及机制

地杆菌属（Geobacter）是迄今最重要的胞外呼吸菌。它们通过胞外电子传递实现厌氧呼吸，在土壤修复、微生物互营共生及生物能源等过程中发挥重要作用。硫还原地杆菌（Geobacter sulfurreducens）是地杆菌的模式种。目前，对G. sulfurreducens胞外电子传递的研究主要集中于菌毛和细胞色素。研究发现G. sulfurreducens大量分泌富含细胞色素的膜囊泡并首尾连接形成纳管。据此，本项目提出“膜囊泡介导的G. sulfurreducens胞外电子传递”假说，采用密度梯度离心分离、纯化膜囊泡，通过质谱分析探明其组成成分，同时采用荧光探针标记、荧光实时成像、透射电镜成像、生物电化学等技术分析膜囊泡/纳管中细胞色素组成与分布、电催化活性，揭示膜囊泡或纳管介导的胞外电子传递途径与机制。本研究将丰富对细菌膜囊泡功能的认知，为Geobacter胞外电子传递机制提供新的线索。

Geobacter are the most important extracellular respiration bacteria. They reduce outer cellular electron acceptors by a way named Extracellular Electron Transfer (EET), and play an important role during waste water treatment, soil bioremediation, the formation of co-culture system and in the anode of microbial fuel cell. The research on the EET of Geobacter mainly focuses on the function of pili and c-type cytochromes of Geobacter sulfurreducens, which is the type culture. Our early data indicate G. sulfurreducens can excrete Membrane Vesicles (MVs) loading with c-type cytochromes, which will further form Vesicle Nanotubes after connect with each other. In this project we advocate a hypothesis that Membrane Vesicles Dependent Extracellular Electron Transfer. The MVs of G. sulfurreducens will be purified first and their molecular identities will be identified by mass spectrometry. Next, the composition and distribution of related c-type cytochromes and the electrochemical catalytic activity of MVs or Vesicle Nanotubes will be analyzed by fluorescent labeling, real-time fluorescence imaging, electron microscopy and bioelectrochemical methods respectively. Finally, the processes and mechanisms under the MVs dependent EET will be concluded. Our research will improve the knowledge of MVs and provide new ideal for the research of EET.