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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2h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。
Extracting the extracellular polymer (EPS) of Acidithiobacillus.ferrooxidans by ultrasonic combined centrifugation, and using 2-keto-3-deoxy octanoic acid (KDO) as an indicator of EPS content, the extraction method was evaluated by spectrophotometry. The effect of EPS on the adsorption of Acidithiobacillus ferrooxidans on the surface of chalcopyrite and pyrite was investigated by a series of comparative experiments. The untreated Acidithiobacillus ferrooxidans and Acidithiobacillus ferrooxidans treated with EPS were re-mixed with EPS suspension, Fe2 + and Fe3 +, and the free bacteria contents in the mixture were detected in real time during 2 hours. The results showed that the presence of EPS on the bacterial surface was an important factor for its adsorption on the surface of pyrite and chalcopyrite. Acidithiobacillus ferrooxidans decreased its ability to adsorb to the mineral surface when the EPS layer was absent, but most of this ability was recovered when the EPS mixture was re-added, a degree of recovery more pronounced in pyrite than in chalcopyrite . When EPS and Fe3 + were added, the bacteria adsorbed on the surface of chalcopyrite increased to a lesser degree, and the adsorption decreased significantly when Fe2 + was added. This result suggests that electrostatic interaction may be one of the main reasons for bacteria initially adsorbed on the mineral surface. And this may be a driving force for bacterial production of EPS to allow bacteria to regain their adsorbability after adsorption to copper sulphide minerals.