低温碱性蛋白酶芽孢杆菌的筛选鉴定及酶学性质研究

本研究从学院食堂附近的土样、人工湖水样和鲫鱼、鲶鱼的肠道中分离得到6株产蛋白酶菌株。经摇瓶发酵复筛后,选择产酶活高的菌株2、菌株5和菌株6进行形态学观察、生理生化鉴定和部分酶学性质研究。结果表明菌株2可能为短短芽孢杆菌,菌株5可能为苏云金芽孢杆菌,菌株6可能为地衣芽孢杆菌。研究3株菌所产蛋白酶的最适pH,发现2号、5号和6号菌株的最适pH分别为6.0、8.0和10.0。菌株5和菌株6所产蛋白酶在pH为8.0~10.0的缓冲液中处理30min后活性几乎不变,在碱性环境中均具有较好的稳定性。菌株5和菌株6所产蛋白酶的最适反应温度均为30℃,低于30℃处理30min活性几乎不变;50℃处理30min后,菌株5和菌株6的残余酶活分别20%和40%。

Screening,Identification and Characterization of a Low Temperature Alkaline Protease Bacillus

Six protease-producing strains were isolated from soil samples,water samples in artificial lake and intestinal tract of crucian carp and catfish near the college canteen.After shaking flask fermentation,strains 2,5 and 6 with high enzyme activity were selected.Then study the morphological observation,physiological and biochemical identification and some enzymatic properties of them.The results showed that strain 2 may be Brevibacterium brevis,strain 5 may be Bacillus thuringiensis and strain 6 may be Bacillus licheniformis.The optimum pH values of protease produced by three strains were 6.0,8.0 and 10.0 respectively.The protease activity of strain 5 and strain 6 was almost unchanged after being treated for half an hour in pH 8.0-10.0 buffer solution,and they were stable in alkaline environment.The optimum reaction temperature of protease No.5 and No.6 was 30 ℃,the activity of protease was almost unchanged under 30 ℃ for 30 minutes,and the residual enzyme activity of strain 5 and strain 6 was 20 % and 40 % respectively after 30 min treatment at 50℃.