Production and Characterization of Protease from Bacillus licheniformis in Solid-state Fermentation Using Deoiled Jatro-pha curcas Seed Cake as Substrate

Abstract:

Solid-state fermentation was employed to produce protease by Bacillus licheniformis using deoiled Jatropha curcas seed cake as substrate. The optimal conditions of protease production were studied. Maximum protease production (7465 U/g of dry substrate, U/g) was obtained at 125% substrate moisture, a growth period of 3 days, supplementation with 10% (wt) of lactose and 5% (wt) of peptone. The results of protease analysis showed that the optimal temperature and pH were 55°C and 5?6, respectively. The Vmax and Km of protease produced by Bacillus licheniformis were 0.0324 μmol/(s?mg) and 0.0531 mmol/L, respectively. Organic solvent can enhance protease activity. In comparison with control, the activities were increased by 13.55% and 70.9% when the protease was solved by 10% (V/V) of methanol and 5% (V/V) of ethanol, respectively. Mg2+ enhanced protease activity by 42.54% while Hg2+ damaged protease and entirely inactive its activity.