高产蛋白酶菌株的筛选及其提高发酵豆粕肽含量效果研究

Screening of a New Bacillus Which Produces High Protease and Study on Its Peptide Promoting Effect on Fermented Soybean Meal

为筛选高产蛋白酶芽孢杆菌并研究其对豆粕的发酵效果,从纳豆、豆豉、健康动物消化道等材料中筛选到一株产蛋白酶芽孢杆菌GCD-2,经形态、生理生化和gyrA基因序列分析确定该菌株为解淀粉芽孢杆菌。对影响GCD-2固态发酵豆粕中肽含量的发酵温度、含水量、接种量、发酵时间和增效剂添加量分别进行单因素和L18(37)正交试验。结果表明:在最优条件下发酵豆粕肽含量由2.24%提高到19.12%;其最优条件为发酵温度32℃、含水量70%、接种量5%、发酵时间72 h、增效剂的添加量为1.0 mg/kg。结果显示,GCD-2可高效降解豆粕中的大分子蛋白,有利于提高豆粕的营养效价及饲用价值。

To screen a bacteria producing protease and study its fermention effect on soybean meal, a Bacillus sp. strain named GCD-2 was isolated from natto, soy sauce, healthy digestive tract and so on. Its taxonomy was established according to morphological features, physiological and biochemical characteristics and gyrA gene sequencesanalysis. Effects of fermention temperature, moisture content, inoculum size, fermentation time and synergist dosage on peptide contents of fermented soybean meal were investigated by single-factor and orthogonal experiments. Results showed that the isolated strain GCD-2 was identified as Bacillus amyloliquefaciens; under optimal fermentation conditions, the contents of peptide were increased from 2.24% to 19.12%; these optimal fermentating conditions were fermentation temperature of 32%, moisture content of 70%, the inculum of 5%, fermentation time of 72 h and lmg/kg dosage of synergist. The results indicated that protease produced by Bacillus amyloliquefaciens GCD-2 can effectively decompose protein in soybean meal, which improved nutritive and feeding value of soybean meal.