Solid-state fermentation for the production of alkaline protease by Bacillus cereus 1173900 using proteinaceous tannery solid waste

Animal fleshing, the major proteinaceous solid waste generated from leather industry, was used as substrate for the production of alkaline protease by Bacillus cereus 1173900 in solid-state fermentation (SSF). Maximum protease activity of 12,310 U/g was observed at 60 h in SSF crude extract. The extracted protease enzyme was purified by 53.64-fold through ammonium sulphate precipitation and chromatography separation in Sephadex G-100. The purified protease had a specific activity of 201.6 (U/mg). The molecular weight of the purified enzyme was 66 kDa, determined by SDS–PAGE. The zymogram also revealed a clear hydrolytic zone due to proteolytic activity, which coincided with the band obtained with SDS–PAGE. Enzyme activity was inhibited by EDTA, suggesting that the enzyme belongs to metalloprotease(s).