Effect of EPS on adhesion of Acidithiobacillus ferrooxidans on chalcopyrite and pyrite mineral surfaces
来源期刊：中国有色金属学报(英文版)2011年第2期
论文作者：余润兰 欧阳 谭建锡 吴发登 孙静 苗雷 钟代立
文章页码：407 - 412
关键词：吸附；A. ferrooxidan；胞外多聚物(EPS)；黄铜矿；黄铁矿
Key words：attachment; Acidithiobacillus ferrooxidan; extracellular polymeric substances; chalcopyrite; pyrite
摘 要：运用超声波结合离心方法提取Acidithiobacillus. ferrooxidans 的胞外多聚物(EPS)，用2-酮基-3-脱氧辛酸(KDO)作为表征EPS含量的指标，采用分光光度法对该提取方法进行评估。通过一系列对比性实验研究EPS对Acidithiobacillus ferrooxidans 在黄铜矿与黄铁矿表面吸附的影响。将未处理的Acidithiobacillus ferrooxidans与经处理脱去EPS层的Acidithiobacillus ferrooxidans 分别与EPS悬液、Fe2+ 和 Fe3+重新混合，在2 h的反应过程中，实时检测混合液中游离的细菌含量。结果表明：细菌表面EPS的存在是其吸附于黄铁矿和黄铜矿表面的一个重要因素。当缺失EPS层时，Acidithiobacillus ferrooxidans 吸附于矿物表面的能力有所下降，但当重新加入EPS混合液时这种能力能大部分恢复，这种恢复程度在黄铁矿中较黄铜矿中更加明显。当加入EPS 和 Fe3+时其细菌吸附于黄铜矿表面的程度有所升高，而加入Fe2+ 时吸附程度明显降低，这个结果表明静电的相互作用也许是细菌最初吸附于矿物表面的一个主要原因，并且这也许是细菌生产EPS的一种驱动力以使细菌吸附于硫化铜矿物后重新获得其吸附能力。
Abstract: Extracellular polymeric substances (EPS) were extracted from Acidithiobacillus ferrooxidans through sonication method associated with centrifugation, which was evaluated tentatively with 2-keto-3-deoxyoctonic acid (KDO) as the indicator of EPS by spectrophotometry. Then the effect of EPS of A. ferrooxidans on the adhesion on chalcopyrite and pyrite surfaces was studied through a series of comparative experiments. The untreated cells and EPS-free cells of A. ferrooxidans were mixed with EPS suspension, Fe2+ or Fe3+, respectively. The planktonic cells were monitored in 2 h during bioleaching. The results indicate that the presence of EPS on the cell is an important factor for the adhesion to chalcopyrite and pyrite. A decrease of attachment of A. ferrooxidans to minerals was produced by the deficiency of EPS, which can recover mostly when the EPS was re-added into the EPS-free cells. The restoring extent is more obvious in pyrite than in chalcopyrite. The extent of cell adhesion to chalcopyrite increased when EPS and Fe3+ added, and decreased when Fe2+ added, which imply the electrostatic interaction plays a main role in initial adhesion between bacteria and minerals and it is a driving force for bacteria to produce EPS probably as a result of regaining their attachment ability to copper sulphides.
