Characterization of iron- and sulphide mineral-oxidizing moderately thermophilic acidophilic bacteria from an Indonesian auto-heating copper mine waste heap and a deep South African gold mine

Iron- and chalcopyrite-oxidizing enrichment cultures were obtained at 50°C from acidic, high-temperature, copper/gold mine environments in Indonesia and South Africa. Over 90% copper yield was obtained from chalcopyrite concentrate with the Indonesian enrichment in 3 months with 2% solids concentration, when pH was maintained at around 2. Neither addition of silver cations nor an enhanced nutrient concentration influenced chalcopyrite leaching. Excision and sequencing of bands from denaturing gradient gel electrophoresis of the amplified partial 16S rRNA gene showed that the enrichment cultures from different environments in South Africa and Indonesia were very simple, and similar. Chalcopyrite concentrate supported a simpler and different community than Fe²⁺. The members of the enrichment cultures were closely related to Sulfobacillus yellowstonensis and Sulfobacillus acidophilus.