A moderately thermophilic acidophilic microbial system "MB-1" was isolated from sulfide mineral. The morphological, microbial community structure and biooxidation characterization of strain "MB-1" were studied. The optimum growth temperature is 46_, and the optimum initial pH is 2.0. The strain can grow autotrophically by using ferrous iron or elemental sulfur as sole energy sources. The strain is also able to grow heterotrophically by using trace peptone. The community structure of the microbial system, which was analyzed by using 16S rRNA gene clone library, is composed of Acidithiobacillus caldus (57%), Acidimicrobium ferrooxidans (10%), Thiobacillus thiooxidans (10%) and Ferroplasma sp. (23%). The results of biooxidation experiments indicate that the strain could oxidize efficiently sulfide concentrate including gold so as to expose the gold for cyanide leaching. The effect of pH, inoculation concentration, pulp density, redox potential, aeration amount and ore particle size on the biooxidation pretreatment process was studied.
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