高产乳糖酶酵母菌的筛选

High yield of yeast lactase screening

以酸马奶酒中分离鉴定的14株酵母菌为材料,进行高产乳糖酶酵母菌的筛选。初筛采用ONPG生化发酵管法和X-gal定性试验,复筛采用ONPG定量试验,分别对阳性菌发酵上清液和菌体破壁液酶活性进行了测定。2种初筛方法结果一致,有8株酵母菌ONPG定性发酵管变为黄色,相应的X-gal琼脂平板上产生蓝色菌落。8株阳性菌ONPG定量试验结果表明,酵母菌J2和J21酶活力远高于其他菌株;菌株J2和J21发酵上清液酶活力高于菌体破壁液,由此确定其所产酶为胞外酶。

In this paper, the high-yielding lactase yeast was screened from 14 strains of yeast isolated from acid kumiss. ONPG biochemical fermentation tube method and X- gal test were used in primary screening. Then, lactase activity of fermentation broth and intracellular fluid was determined in ONPG quantitative test. The same conclusion was reached by two methods of primary screening, eight strains of yeast on ONPG biochemical fermentation tube changed to yellow, and the blue colonies of corresponding yeast was formed on X- gal plate. The conclusion that enzyme activity of yeast J2 and J 21 is much higher than other strains was got by ONPG quantitative test of B strains of positive yeast. The lactase activity of fermentation broth from J2 and J 21 was higher than that from intracellular fluid. So, the enzyme from J2 and J 21 was extracellular enzymes.