| The samples collected from acid mine drainage and sediments in Tongling, Anhui province were cultured by selective media and a strain of iron-oxidizing bacterium AMDSY7-10 was selected from 17 strains of prokaryotic microbes gained from acid mine environment.This paper has studied the biological properties of AMDSY7-10, the result showed that:firstly, the colonial morphology of the bacterium in R2A medium was round and ivory, the surface of the colony was wet and the edge of it was inerratic while in FeT medium was rusty and dry, the surface of the colony was inerratic too; secondly, the cellular morphology of the bacterium was in short rod, and the size (lengthx bandwidth) of the cell was 0.6-1.4μm×0.2-0.4μm, the microorganism did not have spore and fexirubin and it was gram-negative. The optimum pH for growth was 5.5, the optimum growth temperature was 30℃, the optimum growth salinity was 0% and the logarithmic phase of it was 48-72h. The iron-oxidizing bacterium AMDSY7-10 could utilize glucose, sucrose, mannose and so on as sole carbon source while it couldn’t utilize lactose, xylose, maltose and so on. As for the nitrogen source, it could utilize urea, glucosamine but it could not utilize nitrates, phenylalanine. It could not produce hydrogen sulfide and O-F was positive. The 16S rDNA sequence analysis of AMDSY7-10 showed that it belonged to Ralstonia sp. with the ho mo logy of 97.62% to Ralstonia pseudosolanacearum.The study of Fe2+ oxidazing ability of AMDSY7-10 showed that the optimal Fe2+ concentration was 5 mM. It oxidized Fe2+ through contacting way and the oxidizing point may locate at the cells’ outer membranes. The oxidizing-rate was nearly 65μg/(min·mg protein) which was higher than autoxidation, but compared to Acidithiobacillus ferrooxidans, the iron-oxidizing ability was weaker.The pyrite spreads widely in acid mine area and its oxygenolysis is closely associated with the formation of acid mine drainage. This paper has studied the oxidation of pyrite in AMDSY7-10. The study has set up four experimental groups, it showed that iron has great influence in the pyrite oxidation of AMDSY7-10 in the initial reaction system after analyzing the pH, iron and secondary mineral precipitation in pyrite surface through Nonyl phenol method, SEM, EDS, STXM. Meanwhile, the study also explored the affection of illumination, pyrite concentration and pyrite granular size for iron-oxidizing of AMDSY7-10. The result showed that illumination had no influence on the oxidation of pyrite but the oxidizing-rate reached the peak when the pyrite concentration was 0.4%, small pyrite granular size was good for oxidation. The oxidizing-mechanism of the pyrite has combined direct-oxidation and indirect-oxidation, the direct part was that the bacteria attached the surface of pyrite and eroded the pyrite and we found many lytic pits which had similar size with the bacteria in the surface of pyrite. The indirect part was that the ferrous was oxidized to ferric with the help of AMDSY7-10 and the ferric eroded the pyrite also promoted the oxidation of ferrous. The study of AMDSY7-10 in pyrite oxidation has great value for the analysis of acid mine drainage formation, mechanism and bioremediation. |
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