高产蛋白酶菌株的分离、筛选及鉴定

为了降解豆粕中的大分子蛋白为大豆肽，利用酪蛋白平板法作为筛选模型，从土壤中分离和筛选高产 蛋白酶的菌株，选取水解圈直径与菌落直径比值较大的菌株液体发酵后进行蛋白酶活力和大豆肽转化率的测定，结 果得到1 株蛋白酶活力和大豆肽转化率较高的菌株B1，其酶活力达到111.8 U/mL，大豆肽转化率达到37.2%。对该 菌株进行形态观察和生理生化特征分析，初步将其鉴定为芽孢杆菌属(Bacillus sp.）。

Isolation, screening and identification of high protease-producing strains

In order to degrade the macromolecular protein of soybean meal to soybean peptide, casein-plate method was adopted as a screening model in this study. Firstly, high protease-producing strains were isolated and screened from soil, and the strains possessed bigger ratio of hydrolytic circle and colony diameter were selected. After liquid fermentation, protease activity and peptide conversion rate of the strain were measured. Finally, strain B1 was chosen with 111.8 U/mL in enzyme activity and 37.2% in peptide conversion rate. Judged by morphological, physiological and biochemical characteristics, the strain was identified as Bacillus sp.