Breeding of High-yielding ?-galactosidase Strains from Protoplast of Aspergillus niger / 微生物学通报

The protoplasts of original Aspergillus niger strain Uco-3 were treated with the cooperation of UV and ?-ray to obtain the high-yielding strain producing the thermostable ?-galactosidase. Under the optimum conditions of formation and regeneration protoplasts were prepared. According to the interaction of positive mutation rate and radiation dose,the optimum condition was determined. The optimum dose of UV was 4 minutes and the optimum dose of ?-ray was 500 Gy. After mutagenetic treatment of protoplasts and selection from a lot of mutants,a mutant DL116 producing the thermostable ?-galactosidase was obtained. The ?-galactosidase activity of DL116 was increased from 16.27 U/mL to 44.37 U/mL,which was higher than that of strain Uco-3.