A native mesophilic iron-oxidizing bacterium,Acidithiobacillus ferrooxidans,has been isolated (30 ℃) from a typical,lead-zinc concentrate of Dachang Mine in the region of Liuzhou located in the southwest of China.Two typical copper sulfide minerals,chalcopyrite and bornite,were from Meizhou Copper Mine in the region of Guangdong Province,China.Variation of pH and cell growth on time and effects of some factors such as temperature,inoculation cell number,and pulp density on the bioleaching of chalcopyrite and bornite were investigated.The results obtained from the bioleaching experiments indicate that the efficiency of copper extraction depends on all of the mentioned variables,especially the pulp density has more effect than the other factors on the microorganism.In addition,the results show that the maximum copper recovery was achieved using a mesophilic culture.The copper dissolution reached 51.34% for the chalcopyrite while it was 72.35% for the bornite at pH 2.0,initial Fe(Ⅱ) concentration 9 g/L and pulp density 5%,after 30 d.