Properties of ferric-ion reducing system of T. ferrooxidans and molecular cloning of this enzyme

铁氧化细菌氧化亚铁硫杆菌（Thiobacillusferrooxidans）是酸性矿山废水中的一种细菌，在硫化矿细菌浸出中起着重要作用。T.细菌浸出中的氧化亚铁酶可能是由于这种细菌氧化亚铁离子和还原的硫化合物的能力。为了获得更多有价值的细菌浸出菌种，研究硫氧化菌的硫氧化机理具有重要意义。氧化亚铁本项目取得了以下成果。(1)阐明了T.将其从氧化亚铁酶AP 19 -3中分离出来，并将其纯化至电泳均质状态。(2)T.氧化亚铁酶，其中元素硫通过三种酶，即SFORase、亚硫酸盐：三价铁离子氧化还原酶和铁氧化酶的协同作用而被氧化，并且Fe^<3+>和Fe^<2+>在这些酶中起着电子媒介的作用。(3)这一新的硫氧化途径实际上涉及该细菌的好氧硫氧化。(4)探讨了Cu^<2+>和Co^<2+>抑制T.铁氧化物被澄清。(5)探讨了T.铁氧化物被澄清。(6)测定了SFORase的N端氨基酸序列。

The iron-oxidizing bacterium Thiobacillus ferrooxidans inhabits drainage in acid mines and plays a crucial role in the bacterial leaching of sulfide ores. The value of T. ferrooxidans in bacterial leaching may be due to the ability of this bacterium to oxidize both ferrous ions and reduced sulfur compounds. In order to obtain more valuable strains for bacterial leaching, it is important to study the mechanism of sulfur-oxidation in T. ferrooxidans. The folloing results were obtained in this project. (1) The existence of a novel sulfur-oxidizing enzymes or sulfur:ferric ion oxidoreductase (SFORase) was clarified in T. ferrooxidans AP19-3 and it was purified to an electrophoretically homogenous state. (2) A new route for sulfur oxidation other than that previously reported was proposed in T. ferrooxidans, in which elemental sulfur is oxidized by the cooperation of three enzymes, namely, the SFORase, sulfite:ferric ion oxidoreductase and iron oxidase, and Fe^<3+> and Fe^<2+> play a role as mediator of electrons among these enzymes. (3) Evidence that this new sulfur oxidation route actually involves in aerobic sulfur oxidation by this bacterium was pressented. (4) The mechanism for the inhibition by Cu^<2+> and Co^<2+> of the sulfur metabolism of T. ferrooxidans was clarified. (5) The mechanisms for Mn^<4+> and Mo^<6+> reduction with elemental sulfur by T. ferrooxidans were clarified. (6) N-terminal amino acid sequence of SFORase was determined.