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Abstract: A novel Acidithiobacillus ferrooxidans strain QXS-1 was isolated from the acid mine drainage of Qixiashan Pb–Zn–Ag mine area in China. The isolate QXS-1 is a motile, rod-shaped Gram-negative bacterium with an optimum growth at 30°C and pH 2.0. The phylogenetic analysis has demonstrated that QXS-1 is a new strain of A. ferrooxidans. The strain QXS-1 exhibited an unusual trait on the utilization of ferrous iron and sulfur as energy sources. The sulfur-domesticated QXS-1 cells only utilized sulfur as energy source for growth when both ferrous iron and sulfur are available, whereas ferrous-domesticated QXS-1 cells prefer to simultaneously utilize both ferrous iron and sulfur as energy source for growth in the presence of both substrates. The QXS-1 cells accumulated intracellular hydrophilic sulfur during growth. Based on the ultrastructure study, we deduced that the accumulated sulfur in QXS-1 exists in both octasulfur ring form and polysulfide form. The strain QXS-1 exhibited remarkable marmatite-bioleaching capacity. It is able to extract 6585mg/L zinc from marmatite within 18days in shake flask. [Copyright &y& Elsevier]

Laboratory simulation of clogging in the Lixi tailings dam (Shaanxi Province, China) is urgently required because clogging is an important factor affecting the dam stability. This work firstly presents the results of ferrous iron oxidation experiments using buffer solution. The results indicate that the ferrous iron oxidation follows first order kinetics, and the oxidation process is strongly dependent on pH, a higher pH resulting in a higher oxidation rate. Furthermore, when the pH exceeds 7.0, the oxidation rate constant increases significantly. Secondly, a column experiment was carried out under the conditions of the pH ranging from 6.8 to 7.5 and the natural oxygen supply. Ferrous iron oxidation and precipitation were found to reach equilibrium under these conditions. After 23 days, the column experiment was stopped when the clogging materials blocked the column outlet. The clogging materials were found to be a mixture of ferric hydroxide and its converted products, and these existed in amorphous form with a loose cluster microstructure according to the results of XRD and SEM. [ABSTRACT FROM AUTHOR]