葡萄糖对嗜酸氧化亚铁硫杆菌与Acidiphilium acidophilum共培养的影响

Influence of glucose on the co-culture of Acidithiobacillus ferrooxidans and Acidiphilium acidophilum

摘要:

【目的】深入了解自养的嗜酸氧化亚铁硫杆菌(Acidithiobacillus ferrooxidans)与异养的Acidiphilium acidophilum之间的协同作用, 为嗜酸异养微生物在生物浸出体系和酸性矿坑水(AMD)等极端酸性环境中的生态功能研究提供基础, 并为AMD环境的修复提供参考。【方法】应用实时荧光定量PCR (RT-qPCR)及特异性引物, 定量At. ferrooxidans与Aph. acidophilum在类似自然状态下的共培养物受葡萄糖抑制时的生物量变化, 同时检测其生长过程中Fe2+氧化和pH值的变化。【结果】无论是否加入葡萄糖, 共培养对Fe2+氧化的效率均较At. ferrooxidans纯培养高。当葡萄糖浓度为5 g/L时, At. ferrooxidans纯培养失去对Fe2+的氧化能力, 而共培养仍能在100 h内将所有的Fe2+氧化完, 且加入葡萄糖越多的培养体系氧化终点的pH值也越高。在不加入葡萄糖的条件下, At. ferrooxidans 与Aph. acidophilum 数量比在100:1的数量级, 表明以这两种菌为代表的自养菌和异养菌在自然条件下生物量的比例。无论纯培养还是共培养的At. ferrooxidans数量均随葡萄糖浓度的提高而减少, 且延滞期则变长; 而异养生长的Aph. acidophilum则相反。【结论】适合进行Fe2+氧化的At. ferrooxidans与Aph. acidophilum的数量比例范围应在100:1的数量级。由于Aph. acidophilum能促进At. ferrooxidans对亚铁的氧化, 并能缓解或消除葡萄糖对At. ferrooxidans的抑制, 所以不能以加入类似于葡萄糖的有机物作为AMD环境生物修复的手段。

Abstract:

[Objective] To gain a better understanding of the synergic interactions between chemoautotrophic bacteria Acidithiobacillus ferrooxidans and heterotrophic bacteria Acidiphilium acidophilum that usually occurred in bioleaching system and acid mine drainage (AMD). For suggestion on AMD bio-remediation and research foundation on ecology functions of acidophilic heterotrophic bacteria in bioleaching system and AMD environment. [Methods] The biomass dynamics of At. ferrooxidans and its natural co-culture with Aph. acidophilum in 9K-ferrous iron media with or without glucose were measured respectively by quantitative real-time PCR; meanwhile, the pH and Fe2+ oxidation were monitored. [Results] Whether the glucose was added in culture media or not, the Fe2+ oxidation efficiency of At. ferrooxidans is higher in co-culture than that in pure culture. When the concentration of glucose is 5 g/L, pure culture of At. ferrooxidans couldn’t oxidize Fe2+ while the co-culture could finish the Fe2+ oxidation in 100 h, and the pH is higher when more glucose was added in both cultures. Without glucose, the cell number ratio of At. ferrooxidans to Aph. acidophilum in co-culture was about 100:1, which suggested the usual cell number ratio between autotrophic bacteria and heterotrophic bacteria in AMD environment. Both in pure and co-culture, the cell number of At. ferrooxidans decreased and the lag phase prolonged with the increase of glucose concentration; while in the case of Aph. acidophilum in co-culture, the cell number and lag phase showed a reverse trend. [Conclusion] For efficient Fe2+ oxidiation, the proper cell number of At. ferrooxidans should be 100 times higher than that of Aph. acidophilum. Because Aph. acidophilum facilitated the Fe2+ oxidation by At. ferrooxidans and reduced the inhibition by glucose, the addition of organic compounds such as glucose could not be a good AMD bio-remediation strategy.