Abstract

Helium-neon (He-Ne) laser irradiation is a highly efficient mutation breeding technology and is widely applied to various fields of biological science. Using Bacillus subtilis YTB4 with high yield of multienzyme complex as original strain, mutation breeding was carried out by He-Ne laser irradiation in this study. Based on the study of the strains’ survival rate and positive mutation frequency, the appropriate irradiation dose was determined. The mutant YTB4A was selected through see-through circle way and enzyme activity determination. Compared with the original strain the activities of cellulase, protease and amylase increased by 265.14, 35.42 and 172.78%, respectively. In addition, the hereditary stability test showed that the activities of multienzyme complex were stable and that there was no reverse mutation after 25 generations.

Key words: Bacillus subtilis, multienzyme complex, He-Ne laser, mutation, hereditary stability.