LiCl-ARTP复合诱变选育高产碱性蛋白酶菌株及其发酵条件优化

以地衣芽孢杆菌（Baclicus lincheniformis）E-417为出发菌株，采用氯化锂（LiCl）-常压室温等离子体（ARTP）复合诱变法对其进行诱变，通过酪蛋白平板初筛、摇瓶复筛、遗传稳定性验证筛选高产碱性蛋白酶的优良菌株，并通过单因素及响应面试验对其发酵产酶条件进行优化。结果表明，在氯化锂添加量为1.5%、ARTP照射时间为45 s的最适复合诱变条件下筛选得到1株高产碱性蛋白酶的优良菌株F-3，酶活达到12 147 U/mL，且该菌株传代8次后仍具有良好的遗传稳定性，其最适发酵培养基成分为玉米粉41 g/L、豆饼粉40 g/L、碳酸钠2.1 g/L、磷酸氢二钠2.0 g/L；最适发酵条件为发酵温度37 ℃、初始pH值7.0、接种量8%。在此优化条件下，碱性蛋白酶酶活达到16 156 U/mL，较原始菌株提高75%。

Breeding of high yield alkaline protease strain by LiCl-ARTP compound mutation and fermentation condition optimization

Using Bacillus licheniformis E-417 as the starting strain, the strain was induced by lithium chloride(LiCl)-atmospheric pressure room temperature plasma(ARTP) compound mutation, and an excellent strain with high alkaline protease yield was screened through casein plate, shake flask and genetic stability test. The fermentation conditions for enzyme production were optimized by single factor and response surface tests. The results showed that the excellent strain F-3 with high alkaline protease production was screened under the optimal compound mutation conditions with lithium chloride addition1.5% and ARTP irradiation time 45 s, and the enzyme activity reached 12 147 U/ml. The strain F-3 still had good genetic stability after 8 passages. The optimum fermentation medium was corn flour 41 g/L, soybean cake powder 40 g/L, sodium carbonate 2.1 g/L and disodium hydrogen phosphate 2.0 g/L. The optimum fermentation conditions were fermentation temperature 37 ℃, initial pH value 7.0 and inoculum 8%. Under the optimized conditions, the enzyme activity of alkaline protease reached 16 156 U/ml, which was 75% higher than that of the starting strain.