Mechanisms of enzyme-catalyzed dissimilatory Fe(Ⅲ) reduction and its molecular regulation:A review

HUANG Can1,2,WU Hong-dong2,HE Qing-ming2,PENG Xu-ya1,2(1Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment,Ministry of Education,Chongqing University,Chongqing 400044,China;2College of Urban Construction and Environmental Engineering,Chongqing University,Chongqing 400044,China)

dissimilatory Fe(Ⅲ)-reducing bacteria;mechanisms of dissimilatory Fe(Ⅲ) reduction;electron acceptor;molecular regulation

Dissimilatory Fe(Ⅲ)-reducing bacteria are spread throughout the domain of bacteria and archaea.They are phylogenetically diverse and have been isolated under various environment conditions.Unlike other electron acceptors,Fe(Ⅲ) has a very low solubility and exists primarily as insoluble Fe oxide under neutral pH.At present,the mechanisms of gathering and reducing Fe(Ⅲ) are still poorly understood.Taking Shewanella and Geobacter as examples,this paper reviewed three kinds of possible mechanisms of microbial enzyme-catalyzed dissimilatory Fe(Ⅲ) reduction and its molecular regulation,i.e.,direct contact between microbial cell and Fe(Ⅲ) oxides,siderrophores,and electron shuttling compounds.Many membrane-bound cytochrome proteins are involved in the dissimilatory Fe(Ⅲ) reduction,forming a complicated regulation network.This paper also proposed future research directions on the mechanisms of enzyme-catalyzed dissimilatory Fe(Ⅲ) reduction so as to better understand this important biochemical process.