酒曲中凝乳酶产生菌的筛选及其培养条件研究

Screening of the chymosin producing strains and optimization of the culturing conditions in chinese Koji

从14种酒曲中分离纯化出了18株菌株,其中8个具有凝乳酶活力。采用酪平板法和Arima时间法筛选出了1株产生凝乳酶能力强的菌株M12。通过正交试验,获得了M12的最佳培养配方、培养条件。最佳培养基组成为,每1 000 mL培养液含麸皮汁2%,KH2PO40.05%,葡萄糖0.2%,培养液pH值5.8￣6.2。最佳发酵条件为培养温度为31℃,转速140 r/min,培养时间为60 h。优化后的菌株凝乳酶活力最高可达133.3索氏单位(SU)。

In this experiment, 18 fungal strains were isolated and purified from 14 Chinese koji samples. By the petri plate method and Arima technique, according to the clabbering ability and hydrolyzing capacity of the tested strains, a high chymosin producing swain, named M12, was screened, and the optimum culture of M12 was determined by using the orthogonal test. The results suggested that the optimum medium consisted of 20% bran （g/v）, 2% glucose, and 0.05% KH2PO4, and the original medium pH was 5.8-6.2. The optimum culturing conditions were as the following： incubating temperature was 31 ℃, rotating speed was 140 r/min, incubating time was 60 h, and the chymosin activity could reach to 133.3 SU/mL.