Selection of high activity of protease-producing strain based on the mutagenesis on protoplast by ultraviolet

Aspergillus oryzae Shanghai brewing 3.042 was used as the initial strain to prepare protoplasts under appropriate conditions,and then the method of ultraviolet mutagenesis was applied to the protoplasts in order to increase protease activity of the initial strain.After UV mutagenesis treatment of protoplasts and genetic stability test,a high protease-producing strain with 1700U/g was obtained,it was 1.8 times than the initial strain.