Kinetics Study of Extracellular Detergent Stable Alkaline Protease from Rhizopus oryzae

In this study, extracellular alkaline protease was produced from Rhizopus oryzae in submerged fermentation using dairy waste (whey) as a substrate. Fermentation kinetics was studied and various parameters were optimized. The strain produced maximum protease at initial medium pH of 6.0 medium depth of 26 mm, inoculum size of 2% at incubation temperature of 35ºC for 168 h of fermentation. Alkaline protease was purified to homogeneity by ammonium sulphate fractionation followed by sephadex G-100 chromatography. The molecular mass of alkaline protease was 69 kDa determined by 10% SDS-PAGE. The optimum pH and temperature of alkaline protease was 9.0 and 40ºC, respectively. Metal profile of the enzyme showed that the enzyme was non-metallic in nature. The Km , Kcat , Vmax and Kcat/Km values of purified protease were 7.0 mg/mL, 3.8 x102 S-1, 54.30 µmol/min and 54.28 s-1 mg -1.mL respectively, using casein as substrate. The purified alkaline protease had stability with commercial detergents.