嗜酸异养菌对自养菌Acidithiobacillus ferrooxidans金属离子抗性和生物浸出的影响

Influence of acidophilic heterotrophic bacteria on metal resistance and bioleaching by Acidithiobacillus ferrooxidans

摘要:

【目的】了解嗜酸异养菌在诸如酸性矿坑水(AMD)和生物浸出体系等极端酸性环境中对浸矿微生物产生的影响。【方法】研究由嗜酸异养菌Acidiphilium acidophilum和自养菌Acidithiobacillus ferrooxidans经长期驯化后形成的共培养体系分别在Cd2+、Cu2+、Ni2+和Mg2+胁迫下的稳定性; 并将此共培养体系应用于黄铁矿和低品位黄铜矿的生物浸出实验。【结果】在上述4种金属离子分别存在的条件下, 异养菌Aph. acidophilum均能促进At. ferrooxidans对亚铁的氧化, 提高其对能源利用的效率。共培养体系中的异养菌Aph. acidophilum使At. ferrooxidans对Cu2+的最大耐受浓度(MTC)由2.0 g/L提高到5.0 g/L, 而且共培养的细胞数量与2.0 g/L Cu2+条件下生长的At. ferrooxidans纯培养相似。另外, 共培养中的At. ferrooxidans对Mg2+的MTC也由12.0 g/L提高到17.0 g/L。生物浸出实验中嗜酸异养菌Aph. acidophilum促进了At. ferrooxidans对黄铁矿样品的浸出, 浸出率较其纯培养提高了22.7%; 但在含铁量较低的低品位黄铜矿浸出体系中共培养和At. ferrooxidans纯培养的浸出率均低于33%。在加入2.0 g/L Fe2+的低品位黄铜矿浸出体系中, 共培养和At. ferrooxidans纯培养的浸出率均得到提高, 分别达到52.22%和41.27%。【结论】以上结果表明，Aph. acidophilum与At. ferrooxidans共培养在一定的环境胁迫下仍能保持其稳定性并完成各自的生态功能, 并且嗜酸异养菌Aph. acidophilum适合在含铁量较高的浸出体系中与铁氧化细菌共同作用来提高生物浸出的效率。

Abstract:

[Objective] to investigate the influence of acidophilic heterotrophic bacteria on Acidithiobacillus ferrooxidans in extremely acidic environment such as acid mine drainage (AMD) and bioleaching system. [Methods] a co-culture consists of Aph. acidophilum and At. ferrooxidans was separately exposed to four metal ions (Cd2+, Cu2+, Ni2+ and Mg2+) to test its stability. This co-culture was also applied to bioleaching of pyrite and low grade chalcopyrite. [Results] In the metal resistance experiment, heterotrophic bacteria Aph. acidophilum facilitated the ferrous iron oxidation by At. ferrooxidans and improved its efficiency of energy utilization. The maximum tolerant concentration (MTC) of At. ferrooxidans to Cu2+ was improved from 2.0 g/L to 5.0 g/L by Aph. acidophilum, and the cell density of co-culture in 5.0?g/L Cu2+ was almost the same with purely cultured At. ferrooxidans in 2.0 g/L Cu2+. In addition, the MTC of co-cultured At. ferrooxidans to Mg2+ was also improved from 12.0 g/L to 17.0 g/L by Aph. acidophilum. In bioleaching experiment, the pyrite bioleaching efficiency of co-culture increased by 22.70% as compared with that of purely cultured At. ferrooxidans. While in the low grade chalcopyrite bioleaching system with few iron, the bioleaching efficiency of both At. ferrooxidans and its co-culture with Aph. acidophilum were lower than 33%. In the low grade chalcopyrite bioleaching system with pre-added 2 g/L Fe2+, the bioleaching efficiency of At. ferrooxidans and its co-culture with Aph. acidophilum were raised to 41.27% and 52.22%, respectively. [Conclusion] Results in this study demonstrated that At. ferrooxidans and Aph. acidophilum in co-culture could maintain their physiological stability and sustain their ecological function under environmental stress. The bioleaching results suggested that acidophilic heterotrophic bacteria Aph. acidophilum should be applied to the bioleaching system with high iron concentration, in which it could collaborate with iron oxidation bacteria to improve the bioleaching efficiency.