Production and Characterization of Protease from Serratia marcescens
Keywords:Protease, inhibitors, rice bran, purification, termite
AbstractExtracellular protease produced by Serratia marcescens isolated from the gut of termite (Centrocestus formosanus) was investigated in this study. The effect of temperature, pH, carbon and nitrogen sources on protease production was examined. The extracellular protease was separated from the culture supernatant of the organism through precipitation with ammonium sulfate. The protease was purified by Sephadex G-150 gel filtration and diethylaminoethanol (DEAE) - Sephadex A-50 ion exchange chromatography. The effect of temperature, pH, and salts on the proteolytic activity of the enzyme was also investigated. Optimal protease production was obtained after about 12-hour incubation. The optimum temperature and pH for protease production was found to be 40°C and pH 7, respectively. Protease production was highest when rice bran and casein were used as the carbon and nitrogen sources, respectively. The native molecular weight of the protease was estimated to be 56 kDA. The optimal temperature for hydrolysis of casein was 50°C and the optimal pH was 8. The protease was found to be inhibited by ethylenediaminetetraacetic acid (EDTA), NaCl, CaCl2, FeCl2 and HgCl2. Proteolytic activity was however enhanced by KCl. The maximum velocity Vmax and Km values were 40 mg/min/mL and 0.91 mg/mL, respectively.