Abstract

Experiments were carried out to examine the oxido-reduction of manganese by extremely acidophilic Acidithiobacillus spp. grown with either elemental sulfur or molecular hydrogen as electron donor. While there was no evidence for manganese (II) oxidation, dissolution of solid phase manganese dioxide was observed in cultures grown aerobically on both electron donors, though this appeared not to involve reduction of the metal. Solubilization of MnO₂ was much enhanced in cultures incubated anaerobically, even though biomass was smaller, and pH values increased significantly as a consequence of acid dissolution being accompanied by manganese (IV) reduction. Increases in cell numbers correlated with concentrations of soluble manganese in anaerobic cultures grown on hydrogen, demonstrating that iron-oxidizing/reducing Acidithiobacillus spp. can grow in the absence of oxygen using manganese (IV) as sole electron acceptor. Addition of ferric iron to anaerobic cultures further enhanced the reductive dissolution of MnO₂ as a result of its reduction to ferrous iron which then reacted with the solid manganese phase, and confirming that Mn (IV) reduction by iron-reducing acidophiles can proceed both directly and indirectly, involving iron as a shuttle vector. The implications of these findings to developing technologies for bio-processing oxidized metal ore deposits are discussed.

摘要

进行了实验以检查极嗜酸酸性硫杆菌属对锰的氧化还原。以元素硫或分子氢作为电子供体生长。虽然没有锰 (II) 氧化的证据，但在两种电子供体上有氧生长的培养物中观察到固相二氧化锰的溶解，尽管这似乎不涉及金属的还原。MnO _{2 的}溶解在厌氧培养的培养物中显着增强，即使生物量较小，并且由于酸溶解伴随锰 (IV) 减少，pH 值显着增加。细胞数量的增加与在氢气上生长的厌氧培养物中可溶性锰的浓度相关，表明铁氧化/还原酸硫杆菌属。可以使用锰 (IV) 作为唯一的电子受体在没有氧气的情况下生长。在厌氧培养物中加入三价铁进一步增强了 MnO ₂的还原溶解由于其还原为亚铁，然后与固体锰相反应，并证实铁还原嗜酸菌对锰 (IV) 的还原可以直接和间接进行，涉及铁作为穿梭载体。讨论了这些发现对开发生物处理氧化金属矿床技术的影响。