蛋白酶产生菌的筛选及酶学性质研究

从养牛厂附近的土壤中分离得到一株产蛋白酶性质优良的菌株,初步鉴定为芽孢杆菌,对其最适产酶条件进行了研究。试验表明,最适碳源为玉米粉,最适氮源为玉米浆,300mL摇瓶最适装液量为60mL,最适接种量为2%,起始pH值为4.5和6.5时有2个产酶高峰,并对其进行酶学性质的研究。该酶最适温度为65℃,最适pH值为7.5,该酶在50℃以下保温30min酶活仍较高,在70℃以上酶活全部丧失。在pH值7.0～9.0时比较稳定,而在pH值5.0以下时酶活下降很快。金属离子Pb2+,鳌合剂EDTA能抑制蛋白酶的活性,而Fe2+能激活蛋白酶活性。

Screening of Protease-Producing Strains and Research on Enzyme Characterization

From the soil of the raising cow factories,we gathered a strain produced protease.The strain with the highest-yield protease was identified as Bacillus.In addition,the experimental results revealed that the most suitable fermenting conditions for excreting protease were:the carbon and nitrogen sources,corn flour,corn steep liquor;the volume of fermenting liquor of 300 mL flask,60 mL;inoculum size,2%;respectively.And we concluded there were two peaks that produced proteinase in the original pH 4.5 and pH 6.5.The activity of this enzyme was the highest at pH 7.5 and 65 ℃.This enzyme was stable over the range of pH 7.0~9.0 and below 50 ℃,and its enzyme activity was inhibited by Pb2+ and EDTA.Fe2+ can strongly activate the enzyme.