Abstract: Dissimilatory metal reducing bacteria were domesticated with MnO₂ in acidic conditions,and then the MnO₂ color changed from black to white,even colorless.X-ray diffraction analysis indicated that dissimilatory reductive microbes could reduce MnO₂ effectively after domestication.Manganese leaching from pyrolusite was investigated by using dissimilatory metal reducing bacteriaunder acid conditions,with the effluent of bio-hydrogen production as a reducing agent.Single-factor experiments were employed to examine the effects of anaerobic conditions and pH values on the leaching rate of Mn.The removal rate of chemical oxygen demand(COD) and the mechanism were also studied.It was shown that dissimilatory metal reducing bacteria reduced pyrolusite using the effluent of fermentative hydrogen production.The leaching rate of manganese under anaerobic conditions was higher than that under aerobic conditions,and it could reach 98% under the conditions of pH 3.0-3.5 and the leaching time of 3d.For degrading the effluent of bio-hydrogen production under subacid conditions,the COD removal rate could reach 84% when COD in the effluent of bio-hydrogen production was 2612mg·L^-1,and it would be higher with more pyrolusite.