Research on the Mutation Breeding of Acid Protease-producing Strains

Screening the high-yield strains of acid protease from the corn immersion. The high-yield strains of acid protease was named Y-5.0. Mutagenesis studies of Y-5.0 showed that the best conditions of UV mutagenesis: the dilution of bacteria was 10-5, the best exposure time of UV mutagenesis was 20 s, NTG mutagenesis best conditions: NTG concentration was 500 ug/m L, NTG mutagenesis dilution was 10-4, the best action time of NTG mutagenesis was 50 min. By three times of UV and nitrosoguanidine(NTG) mutation alternately breeding screening, we obtained the highest protease activity mutant named N3-15,the activity of Its producing protease reached 12 152 n Kat/m L, far exceeding the activity of the original strain Y-5.0. This strain passed five times and performed a good genetic stability.