产碱性蛋白酶菌株ZK202的鉴定及其诱变

目的]为产碱性蛋白酶菌株在生产中的应用提供依据。方法]从河南省兰考县盐碱地土壤中分离1株产碱性蛋白酶的菌株ZK202,通过形态观察、生理生化试验和16SrDNA序列分析对其进行鉴定。经紫外照射和DES处理后,测定诱变菌株的酶活力。结果]菌株ZK202的形态符合芽孢杆菌属的特征,其16SrDNA序列与短小芽孢杆菌的同源性在99%以上。该菌株为短小芽孢杆菌一个新亚种,命名为Bacillus pumilus ZK202,属中等嗜盐菌。ZK202在氯化钠浓度0～12.5%条件下均能生长,以浓度5.0%时最佳。ZK202在碱性环境中生长良好,当培养基pH值在11.0以上时仍能生长,也属嗜碱性菌。经复合诱变后,菌株Zkud202-4发酵液的酶活力达321U/ml,比出发菌株高3.9倍。结论]Zkud202-4具有稳定的产酶性能,可作为产碱性蛋白酶的突变菌株。

Identification and Mutagenesis of Strain ZK202 Producing Alkaline Protease

Objective] The aim of the research was to provide basis for applying the strain producing alkaline protease in the production.Method] A strain producing alkaline protease ZK202 was separated from the soil of saline land in Lankao county and identified though morphological observation,physiological and biochemical test and 16S rDNA sequence analysis.After ultraviolet irradiation and DES treatment,the enzyme activity of the induced strain was determined.Result] The morphology of strain ZK202 accorded with the characteristics of Bacillus and the homology between its 16S rDNA sequence and Bacillus pumilus was above 99%.The strain was one new subspecies of B.pumilus,naming Bacillus pumilus ZK202,which belonged to medium halophilic bacteria.ZK202 could grow well under the conditions of 0～12.5%NaCl,with 5.0%NaCl best.ZK202 grew well in alkaline environment and it could still grow when pH value of medium was over 11.0,so it also belonged to basophilic bacteria.After the compound mutation,the enzyme activity of the fermentation liquid of Strain Zkud202-4 reached 321 U/ml,3.9 times higher than that of the original strain.Conclusion] Zkud202-4 had stable performance of producing enzyme and it could be taken as the mutant strain of producing alkaline protease.