为了确定庆阳豆豉的主要作用微生物,获得优势发酵菌株,以甘肃庆阳7个县区农户所制的发酵豆豉为材料,采用不同培养基分离纯化,通过平板透明圈法初筛,发酵液蛋白酶、纤维素酶和淀粉酶活性测定,对传统豆豉发酵微生物进行了分离筛选,最后对优势菌株进行生理生化鉴定及16S rDNA分子生物学鉴定。共分离出22株细菌菌株,初筛获得10株均可分解蛋白质、淀粉和纤维素能力的菌株,其中QY2b蛋白酶和纤维素酶活性最高,分别达到了25.37 U/mL和6.015 U/mL。通过对QY2b的形态观察及生理生化试验,结合16S rDNA鉴定手段,确定该优势发酵菌种为枯草芽孢杆菌(Bacillus subtilis)。

To confirm the main microbes in Qingyang Douchi and gain the predominant strains,experimental samples were collected from douchi made by peasant household in 7 counties of Gansu Qingyang.Predominant strains were isolated and purified through plate streaking.Through clear zone method and determination of the activities of protease,cellulase and amylase,predominant strains were isolated.Strains were identified with physiological and biochemical characteristics and the 16S rDNA analysis.The results revealed that 22 strains of bacteria were isolated from samples,10 strains of them were able to degrade protein,starch and cellulous.Activity of bacterium QY2b in fermentation liquid was highest,the protease activity was 25.37 U/mL and the cellulase activity was 6.015 U/mL.The results of the physiological and biochemical identification and the 16S rDNA analysis showed that it belonged to Bacillus subtilis.