蛋白酶高产菌株的紫外诱变选育

［目的］提高地衣芽孢杆菌B7的产蛋白酶能力。［方法］采用福林酚法测定酶活力，通过诱变育种试验和遗传稳定性试验选育出遗传性能稳定的蛋白酶高产菌株。［结果］紫外线照射时间为2 min，菌落的总致死率为62.47%。371株菌株的HC值变化小于5%，53株菌株的HC值正变大于5%，76株菌株的HC值负变大于5%。正变大于10%的12株菌株的HC值是出发菌株的1.18-1.34倍。所有变异株的蛋白酶活力均显著高于出发菌株，其中菌株B720和B749的蛋白酶活力达50 U/ml，比出发菌株提高了40%以上。经过复筛得到菌株B7 49，诱变前后其最高酶活分别为33.97和50.29 U/ml。遗传稳定性试验中菌株B749的蛋白酶活力变化小于10%。［结论］该试验成功选育出的遗传性能稳定的蛋白酶高产菌株B749可用于发酵法制备大豆肽。

UV Mutagenesis Breeding of High-yielding Strain of Protease

[Objective] The study aimed to enhance the capability of producing protease of Bacillus licheniformis B7.[Method] The enzyme activity was determined by Folin-phenol method and the high-yielding strain with stable genetic property of protease was bred through mutagenesis breeding experiment and genetic stability experiment.[Result] When UV irradiation time was 2 min,the total lethality rate of colonies was 62.47%.The variation of HC values of 371 strains was less than 5%,the positive variation of HC values o...