Mutation Breeding of High-yield Strain of Cellulase

[Objective] The aim was to select effective method to breed high-yield strains of cellulase.[Method] Using Aspergillus niger as starting strain,the mutant with high enzyme activity were bred after compound mutation of ultraviolet and nitrite mutation for the further culture,and then its enzyme activity was detected.[Result] The effect of ultraviolet was obvious better than that of nitrite mutation in single factor mutation and the mutagen dosage with 70%-80% lethality was more ideal.The effect of compound mutation was better than that of single factor mutation.The enzyme activity after compound mutation was improved and the growth speed of strains was accelerated.The characters of strains were stable in many passage experiments.The starting strains mutated through compound mutation of ultraviolet(15 W,the irradiation distance of 30 cm and irradiation time of 8 min) and nitrite mutation(treated with 0.1 mol/L NaNO3 for 5 min) were screened in repeat to obtain the high-yield strain of cellulase,whose cellulase activity was improved by 61.10% and the activity of filter paper enzyme was improved by 64.01%.[Conclusion] Compound mutation with ultraviolet and nitrite mutation could breed strains with high cellulase activity.