ABSTRACTBioleaching of sulfide minerals at neutral pH has been rarely reported. In this study, a bacterium, Bacillus megaterium QM B1551, was isolated from Jinchuan sulfide tailings and used to leach a complex sulfide flotation concentrate for the extraction of Co2+, Ni2+ and Cu2+ at near neutral pH. A total of 38.2% Co, 44.7% Ni and 3.6% Cu were extracted from the sulfide concentrate in 5 days with an initial pH of 6. An enhanced Co2+, Ni2+ and Cu2+ extraction extent was achieved by first bioleaching the concentrate with Bacillus megaterium QM B1551 at 35°C and then followed by chemical leaching with 4 M sulfuric acid at 90°C. As a result, a total of 60.7% Co2+, 76.3% Ni2+ and 39.8% Cu2+ were extracted. On an industrial scale, the profits from the metal recovery by such a combined leaching procedure are optimum if considering the cost-benefit ratio.