中文摘要：

厌氧条件下微生物将电子传递给胞外电子受体的现象非常普遍,电子穿梭体（electron shuttle,ES）是介导胞外电子传递过程的重要途径之一,但其具体的机制尚未明晰。一部分微生物自身能分泌一些物质作为内生ES,另一部分微生物能利用天然存在或人工合成的某些物质作为外生ES,并将其携带的电子传递至微生物胞外电子受体。ES介导微生物胞外电子传递的基本过程为：氧化态电子穿梭体（ESox）接受电子变成还原态（ESred）,ESred传递电子给胞外电子受体,自身再次氧化成ESox,从而循环往复。本文重点介绍不同种类ES及其电子穿梭机制,以及ES的分子扩散、氧化还原电势及电子转移能力对胞外电子传递过程的影响。ES介导的胞外电子传递过程直接影响污染物转化和微生物产电,因此在污染修复及生物能源等方面具有重要的应用前景。

英文摘要：

Under anaerobic conditions,many microorganisms are capable of extracellular respiration involving electron transfer to or from extracellular substrates such as iron（ hydr） oxides and humic substances. Electron shuttling is one of the significant strategies for extracellular electron transfer,however,the involved mechanism has not been thoroughly understood. Electron shuttles can be divided into endogenous electron shuttles that are self-produced by microbes themselves and exogenous electron shuttles that are natural substances or artificially synthesized materials. Electron shuttle-mediated extracellular electron transfer generally involves the following reactions： the oxidized form of electron shuttles（ ESox） accept electrons from the oxidization of organic matter and become as the reduced form of electron shuttles（ ESred）,then ESred transfer electrons to extracellular electron acceptors and return to ESox. Through these steps,electron shuttles can be reversibly oxidized and reduced. This review mainly focuses on the electron transfer mechanisms of different electron shuttles,and the factors affecting extracellular electron transfer such as the molecule diffusion,redox potential and electron transfer capacity of electron shuttles. Electron shuttle-mediated extracellular electron transfer has significant influence on contaminants degradation and microbial electrogenesis,thus the better understanding of their mechanisms is very important to their implications in bioremediation and bioenergy.