【Title】Isolation and study of a psychrotrophic bacterium producing protease from Antarctica
【摘要】从南极中山站地区分离到1 株产胞外酸性蛋白酶的革兰氏阴性杆菌。该菌能在7°C、20°C 及30°C 生长并产酶; 其最适生长温度在20°C 左右, 不耐盐。碳源物质中, 葡萄糖对菌株的生长有利, 但对蛋白酶的生成影响不大; 氮源物质中, 蛋白胨对菌株的生长及蛋白酶的生成效果最好, 而( NH4) 2SO4 则是效果最好的无机氮源。该菌所产胞外蛋白酶占其蛋白酶总量的83°C 2%, 蛋白酶反应的最适温度为40°C , 最适pH 为5; 酶活力在35°C 以下保持稳定。直接以酪蛋白液为培养基、在20°C 条件下对该菌进行摇瓶培养, 6d 后菌液浓度及产酶量皆到达高值并基本保持稳定; 而以LB 培养基( Luria- Bertani 培养基) 在相同条件下培养该菌, 3d 后菌液浓度即到达高值并基本保持稳定, 酶活力则在2d 后到达高值。
【Abstract】A psychrotrophic Gram negative bacterium producing acid protease was isolated from Zhongshan
Station,Antarct ica.This strain could grow and produce protease at 7°C ,20°C and 30°C ,espectively. Optimum growth temperature of the strain was about 20°C . This bacterium could not tolerate high salinity.Among the carbon sources glucosewas the optimal material for growth of the bacterium, however it has nothing to do with the producing of bacterium°C s protease. Peptone was the optimal nitrogen source for growth and protease producing of the strain, and ammonium sulfate was the optimal inorganic nitrogen source. About 83. 2% of total protease of this strain were extracellular enzyme. The optimal temperature and pH for proteolytic activity were 40°C and 5, respect ively. The protease kept stable when temperature no higher than 35°C . The strain was grown in casein solution at 20°C with vigorous shaking. After 6 days, cell number and protease activity of the solution reached high values and kept fairly stable therefrom. In the same culturing condit ions instead with LB media, cel number and protease activity of the solution reached high values after 3 days and 2 days, respectively.