The mobilization of nickel from sulphide minerals using sulfuric acid and Bacillus subtilis was examined. The influences of the concentration of acid and bacteria as well as reaction time were considered. Recovery of nickel by interrupted bioreaction was relatively low and exhibited two phases: an active phase (up to 6 h exposure) and a latent phase (over 6 h exposures) reflecting bacterial inhibition by nickel overtime. Nickel was quickly recovered from tailings (20 ppm/h) than from ore (8.07 ppm/h) with biological and acidic methods. It therefore appears that optimum nickel mobilization with B. subtilis will occur in the active phase. Biological method has environmental advantage and thus appropriate for tailing dumps management. (C) 2010 Elsevier Ltd. All rights reserved.