嗜酸硫杆菌属硫氧化系统研究进展  

Progress on Researches of Sulfur Oxidation System of Acidithiobacillus spp.

作　　者：张成桂[1] 夏金兰[1] 王晶[1] 邱冠周[1] 

机构地区：[1]中南大学资源加工与生物工程学院,长沙410083

出　　处：《生物技术通报》2007年第1期59-65,共7页Biotechnology Bulletin

基　　金：973计划"微生物冶金的基础研究"项目(2004CB619201)

摘　　要：硫化矿的酸溶解和化学氧化过程中(H+和Fe3+作用下,金属硫化矿中分解),伴随着硫元素转变成多聚硫S8或硫代硫酸盐的过程。对嗜酸硫杆菌属硫氧化过程的研究表明,胞外环状多聚硫S8可能通过细胞外膜蛋白巯基活化成线状-SnH后,被转运到细胞周质区域,进而被硫加双氧酶氧化成SO32-,活化过程中同时生成少量H2S;这些酶促反应不需要辅助因子参与,不释放电子。胞外硫代硫酸盐通过未知途径进入细胞周质。细胞周质中的SO32-主要经由亚硫酸-受体氧化还原酶氧化成SO42-,S2O32-可能经由硫代硫酸盐-辅酶Q氧化还原酶、硫代硫酸盐脱氢酶、连四硫酸盐水解酶等氧化为硫酸,少量H2S则经由硫化物-辅酶Q氧化还原酶氧化为多聚硫,后者再经由SO32-和S2O32-氧化生成最后产物SO42-。这些生物氧化过程释放的电子进入呼吸链参与产生细菌生长代谢所需的能量。然而,关于A.ferrooxidans硫氧化系统中各种硫化合物的酶催化氧化机制的研究仍很缺乏,胞内外硫化合物的转运机制、是否存在胞外酶催化氧化等仍然有待解决。另外,硫的型态和价态、酶催化反应的细胞微区域以及硫氧化系统中一些关键酶的分离及其表达基因的鉴定等问题都还有待进一步研究。基于对这些事实的分析,提出了一个嗜酸硫杆菌属硫氧化系统的模型。The metal sulfide solubilization processes were considered to be largely chenfical ways in which the sulfur in a mineral was oxidized with Fe^2＋ by either polysulfide pathway or thiosulfate pathway into polysulfur Ss and thiosulfate,respectively. Researches on the sulfur oxidation process of Addithiobacillus spp. showed that the extracellular polysulfur （Ss）is probably mobilized by thiol groups of special outer-membrane proteins and transported into the periplasmic space as persulfide sulfur （-S2H）,and then oxidized by periplasmic sulfur dioxygenase into SO3^2- accompanied with release few of H2S. These enzymatic reactions may do not need any cofactor and do not release electrons. The extracellular thiosulfate was transported into the periplasmic space by an unknown way. The SO3^2- in the periplasmic space is mainly oxidized into SO4^2- by sulfite： acceptor oxidoreductase,and S2O3^2- is oxidized into SO4^2- possibly by thiosulafte：quinone oxidoreductase,thiosulfate dehydrogenase and tetrathionate hydrolase. The few H2S is oxidized by sulfide：quinone oxidoreductase into Ss that may be further oxidized by ways of S2O3^2- and SO3^2- to the final SO4^2-. These bio-oxidafion processes need some cofactors and release electrons that transfer to the respiratory chain for production of energy required for the cellular growth. Yet,it is very lack in research on the oxidation mechanism of the sulfur-containing compounds,and it is still unresolved how the sulfur-containing compounds are transported through the membranes or whether there exist additional membrane-bound enzymes that catalyze oxidation of the sulfur-containing compounds at the outside of the membrane. Moreover,the purification and gene-expression identification of the key enzymes,the speciation of sulfur,and the enzymatic reactions micro-region pertinent to the oxidation of reduced sulfur-containing compounds are also to be addressed in much more details. Based on the analyses of these facts,in this article, a model of sulfur oxidation system o

关 键 词：硫氧化系统 嗜酸硫杆菌属 硫加双氧酶 硫化物-辅酶Q氧化还原酶 硫代硫酸盐-辅酶Q氧化还原酶 硫代硫酸盐硫转移酶 亚硫酸-受体氧化还原酶 连四硫酸盐水解酶 

分 类 号：Q936[生物学—微生物学]