高产蛋白酶芽孢杆菌的选育及其在大豆活性肽制备中的应用

Mutagenesis of high yield protease spore-forming and its application in soy-peptide preparation

为降低抗生素替代品———大豆活性肽绿色饲料添加剂的生产成本 ,采用紫外线与亚硝基胍 (NTG)多重诱变的方法选育芽孢杆菌CAU2 0 8,以提高产蛋白酶能力。结果显示 :15W紫外灯最适照射时间 3min ,距离 30cm ;亚硝基胍最适质量浓度为 1mg/mL ,且效果好于前者 ,两者复合诱变比单一诱变效果好。将诱变选育的蛋白酶高产菌株No .111用于液态发酵制备大豆肽饲料添加剂 ,6 0h发酵液的水解度为 2 6 9% ,比母本菌株CAU2 0 8的水解度 18 5 %提高了 8个百分点。如果两者达到相同的水解度 (19 0 % ) ,则No .111比CAU2 0 8的发酵周期缩短约 12h。

In order to reduce the cost of soy-pepetide production, a high yield protease strain from its parent strain CAU208 was screened by treating with UV and NTG. The results showed that the optimum conditions of UV were 3min,30cm, and the suitable concentration of NTG was 1000μg/mL,although the effects of NTG were better than UV, but the combined use of UV with NTG was better than single. At the cycle of 60h,the degree of hydrolysis(DH) of No.111 was 26.9% and increased by 42.3% compared with CAU208. To achieve the same DH(19.0%), No.111 fermentation cycle could shorten about 12 hours than CAU208 in producing soy-peptide. No.111 genetic quality was proved to be stable by experiments.