产蛋白酶菌株的筛选及其在固态发酵豆粕中的应用

The isolation of a protease-producing strain and the effect of its solid fermentation on soybean meal

目的:筛选高产蛋白酶菌株,探究微生物发酵对豆粕抗原蛋白的影响,以期提高豆粕在水产饲料中的使用价值。方法:从土壤样品中筛选出1株蛋白酶酶活为1390.6±12.5 U/mL的菌株LX-6,经生理生化特性和16S rDNA分子鉴定为解淀粉芽孢杆菌(Bacillus amyloliquefaciens)。通过B.amyloliquefaciens LX-6不同时间发酵豆粕,分析SDS-PAGE中大分子抗原蛋白降解情况、发酵样品总蛋白以及水溶性蛋白含量。结果:在37℃、物料含50%水的条件下,发酵24 h豆粕中大分子抗原蛋白全部降解,48 h时水溶性蛋白含量达到最高44.45%。结论:B.amyloliquefaciens LX-6发酵后有效提高了豆粕的蛋白含量,此发酵豆粕有望今后开发成水产饲料。

Aims:In order to improve the use value of soybean meal in aquatic feed,we isolated a strain with high protease activity and further investigated its fermentation effect on soybean meal antigen protein.Methods:An aerobic strain LX-6 with protease enzymatic activity of 1390.6±12.5 U/mL was screened from soil samples and identified as Bacillus amyloliquefaciens based on physiology biochemistry characteristics and an analysis of the 16 S rDNA gene.Soybean meal was fermented by B.amyloliquefaciens LX-6.The degradation of antigen protein,the content of total protein and water-soluble protein were determined by SDS-PAGE at different fermentation time points.Results:The results showed that under the conditions of 37℃and 50%water in the substrate material,the macromolecular antigen proteins were completely degraded in 24 h.And the concentration of water-soluble proteins reached 44.45%in 48 h.Conclusions:The total protein concentrations of soybean meal were significantly improved due to the fermentation of B.amyloliquefaciens LX-6 compared to that of the original soybean meal.This fermented soybean meal is expected to be developed and used as an aquatic feed in the future.