地衣芽孢杆菌固态发酵麻疯树饼粕产蛋白酶及其酶学性质

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

摘要:

利用地衣芽孢杆菌作为出发菌株, 以提油后的麻疯树饼粕作为培养基, 采用固态发酵方式生产蛋白酶。控制培养基湿度为125%, 添加10%的乳糖和5%的蛋白胨, 30°C条件下发酵3 d, 蛋白酶产量达到最大值(7465 U/g)。酶学性质研究表明, 蛋白酶最适作用pH为5?6, 最适催化温度为55°C, 最大催化速度Vmax为0.0324 ?mol/(s?mg), Km值为0.0531 mmol/L。有机溶剂对酶活力有明显促进作用, 10% (V/V)甲醇和5% (V/V)乙醇可以使酶活力分别提高13.55%和70.9%。Mg2+可以使蛋白酶活力提高42.54%, 而Hg2+却使酶彻底失活。

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.