As a kind of disaccharidase, lactase could decompose lactose into galactose and glucose, and thus ap- plied into dairy production, medical aid digestion, fruit mature softening and environmental protection and so on. As the main source of lactase, microorganism had many characteristics such as fast growing speed, rich enzyme amount, low production cost, and thus was suitable for industrial production. The study of microorganism lactase was mainly focused on the development of lactase-producing microorganisms and application of lactase gene engineering. Herein the research on the characteristic...