RESUMO
The aims of this research were to isolate a Aspergillus niger strain with higher beta-glucosidase activity. We utilized the beta-glucosidase producing strain Aspergillus niger CGMCC 3.316 as the original strain to first obtain a mutant 3-3M through ultraviolet irradiation. Then we studied the conditions of protoplast release and regeneration for strain 3-3M. We treated the protoplasts of strain 3-3M via ultraviolet irradiation and obtained another isolated mutant 60B-3D. The strain 60B-3D showed much higher beta-glucosidase production than the original strain and 3-3M strain. The beta-glucosidase activity of strain 60B-3D was 23.4 IU/mL, with an improvement of 39% compared with the original strain, and 23% compared with strain 3-3M. We also studied the fermentation process of strain 60B-3D, and compared it with the original strain and strain 3-3M. We found the strain 60B-3D exhibited an improvement in xylanase production. The comparison results also showed that the strain 60B-3D secreted more protein. These results were beneficial for producing beta-glucosidase through this productive mutant.