酒曲中高产蛋白酶菌株的筛选及其发酵培养基优化

Screening and fermentation medium optimization of high-yield protease-producing strain from Jiuqu

从传统酒曲中分离鉴定高产胞外蛋白酶的菌株,探究其生长特性,通过酪蛋白平板法、福林酚法筛选高产蛋白酶菌株,并通过形态特征、生理生化试验、16S rDNA序列分析和种特异性基因分析鉴定菌株。采用单因素试验、Plackett-Burman试验、最陡爬坡试验及Box-Behnken试验优化其发酵培养基。结果表明,分离筛选出一株高产蛋白酶菌株(编号为JQ-2)被鉴定为枯草芽孢杆菌(Bacillus subtilis)。菌株JQ-2最佳发酵培养基为:马铃薯浸出粉5.4 g/L、麦芽浸膏1.8 g/L、牛肉膏10.0 g/L。在此优化条件下,菌株JQ-2的胞外蛋白酶活性为154.75 U/mL,是未优化培养基的14.77倍。

High-yield extracellular protease-producing strains were isolated and identified from traditional Jiuqu and their growth characteristics were explored.High-yield protease-producing strains were screened by casein plate method and Folin-phenol method,and the strains were identified by morphological characteristics,physiological and biochemical tests,16S rDNA sequence analysis and species specific gene analysis.The fermentation medium was optimized by single factor tests,Plackett-Burman tests,the steepest climbing tests and Box-Behnken tests.The results showed that a high-yield protease-producing strain was isolated and screened(numbered as JQ-2),and identified as Bacillus subtilis.The optimal fermentation medium of the strain JQ-2 was as follows:potato extract powder 5.4 g/L,malt extract 1.8 g/L and beef extract 10.0 g/L.Under these optimal conditions,the extracellular protease activity of the strain JQ-2 was 157.75 U/ml,which was 14.77 times that of unoptimized medium.