[Studies on the screening high yield acid protease producing strain L336 by combining microwave irradiation with chemical inducing].

A high yield acid protease producing strain Aspergillus usamii L336 was screened from its parent strain B1 by combining microwave irradiation with inducing of nitrosoguanidine and Li2SO4. By incubation of L336 in shaking flask at 31 degrees C for 88 h, its enzyme activity was 5500 u/mL, and its properties for high yield producing acid protease remained stable after many times of subculture and storage for two months.