筛选分离得到一株高产碱性蛋白酶菌株EIM-8,并基于16S序列进行分子系统进化分析,鉴定该菌株为枯草芽孢杆菌(Bacillus subtilis).同时,采用响应面法对Bacillus subtilis EIM-8的产酶条件进行了优化.首先通过单因素试验,筛选出最适碳源为玉米淀粉,最适氮源为牛肉膏.在此基础上,采用Plackett-Burman试验设计筛选出影响酶活的三个主效因子--玉米淀粉、装液量和初始pH值.再通过最陡爬坡实验逼近最大响应区域,用Box-Behnken试验设计和嵴岭分析确定主效因子的最优水平.优化后酶活可达10 232.2 U/mL,较优化前提高了2.53倍.%A high alkaline protease-producing strain EIM -8 was isojated and identified as B acillus subtilis based on its phylogenetic analysis of 16S sequence . And then the ferm entation conditions for B acillus subtilis EIM -8 for producing alkaline protease were investigated . First the carbon and nitrogen sources were determ ined as com starch and beef extract by single factorial experiments . Then some process factors in subm erged ferm entation were evaluated and three significant factors : comstarch , the liquid volume and the initial pH , were obtaied by Plackett-Bum an design . At last the optimal ferm entation conditions were determ ined by the Box-Behnken design and ridge analysis after the steepest ascent search experinent. The maxinum activity of alkaline protease produced by Bacillus subtili's EIM -8 reached up to 10 232 .2 U/m L and the yield was incrased by 35.3％ compared with that of the original .
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