Bioremediation is the removal of heavy-metals such as nickel (Ni) using microorganisms and has been considered as an important field in the biotechnology. Isolation and characterization of microorganisms exhibiting bioremediation activities and their optimization to treat polluted wastewaters is a vital and difficult task in remediation technologies. In this study, investigation was carried out to isolate Ni (II) remediating microbial strains from soils contaminated with municipal solid waste leachate. Furthermore, Taguchi design of experiments were used to evaluate the influence of concentration, pH, temperature, and time on bioremediation of Ni (II) using isolated bacteria. This study concluded that