Traits main role is the hydrolysis of lactose to glucose and galactose. The optimum pH value: 7.0 ~ 7.5 by the Escherichia coli (E. Coli) was prepared by,; by yeast system for the 6.0 to 7.0; by fungi obtained about 5.0. The optimal temperature of 37 ~ 50 ℃. The concentration of normal use, can make about 74% hydrolysis of lactose within 72 h. 
 The use of the method is mainly used for the dairy industry. Allows low sweetness and low solubility of lactose into the sweet, the greater solubility of monosaccharides (glucose and galactose); make ice cream, condensed milk, evaporated milk, lactose crystallization less likely, while increasing sweetness . Can make can not use general yeast lactose hydrolysis into glucose in the fermentation and baking industries, to be exploited. There are a certain number of babies because of the enteral lack of normal lactase enzyme cause of diarrhea after feeding milk, and many European countries is often lactase and lysozyme added to the milk for the baby to drink.