异化铁还原是厌氧环境中铁氧化物微生物转化的主要形式，是沉积物中物质能量转化和电子传递的重要途径之一，由于环境条件的复杂性，微生物异化铁还原过程的胞外电子传递一直没有得到清晰认识。本项目基于异化铁还原过程主要由铁还原微生物纳米导线pili介导的胞外电子传递过程的思路，拟以我国典型亚热带河口和近海沉积物为代表采集样品结合室内模拟实验，利用微结构分析技术联合现代分子生物学技术，阐明纳米导线pili的组成、结构及在胞外电子传递过程中的作用；揭示不同环境条件下包括不同形态和尺度铁氧化物、盐度、营养条件等对微生物纳米导线pili异化铁还原过程的影响；探索沉积物颗粒中铁还原微生物组成、纳米导线pili的分布及对异化铁还原的规律；揭示生物纳米导线pili在河口沉积物铁还原过程中的作用机制，阐明河口异化铁还原过程微生物纳米导线作用机制，为丰富地球生物学理论和金属污染控制和修复以及有机碳转化提供理论依据。

The reduction of Fe(III), by Fe(III)-reducing microorganisms can play an important role in carbon cycling in water-saturated soils and aquatic sediments and further influence the geochemistry of these environments through the release of dissolved Fe(II) as well as heavy metals, metalloids, and phosphate that adsorb onto Fe(III) oxides. Although much work about extracellular electron transfer in Fe(III)-reducing microorganisms-Geobacter species had been done, the mechanisms of extracellular electron transfer in the reduction of Fe(III) have not yet to be described clearly. The proposed research will demonstrate that the possibility of electron transport is along protein filament pili and the metallic-like mechanism for electron transport along the pili is a fundamental process in reduction of Fe(III) in sediments. The samples will be collected from the estuarine sediments in Fujian Province. The research proposed here will analyze the component, structure of pili and its function in extracellular electron transfer, ascertain the distribution of pili in sediment aggregates, explore the mechanisms of the reduction of Fe(III) by nanowire pili of Fe(III)-reducing microorganisms,determine the mechanisms of reduction of Fe(III) along the Fe(III)-reducing microorganisms pili in sediments for extracellular electron transfer. The results of research will explain the primary process of the reduction of insoluble Fe(III) oxides and coupling the oxidation of organic compounds in many soils and sediments.