大曲中高产糖化酶菌株的筛选及产酶条件优化

The High-yield Glucoamylase Strains in Daqu: Screening and Optimization of Enzyme Production

为了获得高产糖化酶的菌株并用于强化大曲的生产,以张弓老酒大曲为试材,通过透明圈法进行初筛以及测酶活法进行复筛,从中筛选了一株高产糖化酶的菌株WD11,其初始酶活为101 U/mL,然后通过16S rDNA序列同源性分析可以初步将该菌株归于芽孢杆菌属。在此基础上,又对其进行生理生化特性研究分析,结果表明甲基红试验、V.P试验、硝酸盐及鸟氨酸反应显阳性,赖氨酸呈阴性,故可以确定菌株WD11为解淀粉芽孢杆菌(Bacillus amyloliquefaciens)。后采用正交试验法进行了产酶条件优化,结果表明:在固体发酵培养基上,当以高粱面为最适碳源(质量分数2%),以蛋白胨为最适氮源(质量分数4%),接种量为6%时,其糖化酶活可达160 U/mL,是初始酶活的1.6倍,预期可以提高白酒的出酒率。

To obtain the strains with high-production glucoamylase and strengthen the production of Daqu,with Zhang Gong Liquor Daqu as test material, a strain WD11 with high-production glucoamylase was screened initially with the transparent circle method and re-screened through measuring enzyme activity method.The initial enzyme activity was 101 U/mL, and the strain was preliminarily determined and belonged to bacillus genus by 16S rDNA sequence homology analysis.Based on the above, the strain was also studied by the physiological and biochemical characteristics analysis.The results showed that methyl red test, V.P test,nitrate and ornithine reaction presented positive, lysine showed negative.Therefore, WD11 strain was identified as Bacillus amyloliquefaciens.After that, the conditions of enzyme production were optimized by orthogonal experiment.The results showed that, on the solid fermentation medium, with the sorghum flour as the optimal carbon sources(mass fraction 2%), peptone as the optimal nitrogen source(mass fraction 4%), and the inoculated quantity of 6%, the saccharifying enzyme activity was up to 160 U/mL, which was 1.6 times that of the initial enzyme activity.The strain is expected to increase the liquor yield.