Study on the conditions for producing the cellulase by mutant strain of Aspergillus niger ZM-8

The selected mutant Aspergillus niger ZM-8 had high yield of cellulase,its β-glucosidase activity was especially high.The conditions for producing enzyme were optimized by orthogonal experiment.The optimum component of medium for enzyme production were as follows:(NH4)3PO4 as nitrogen source,0.6 % nitrogen,300 % water,the quality ratio of corn straw powder to wheat bran was 4∶1,the inoculation quantity was 1∶30.The optimum culture conditions were 35 ℃ for 72 h with initial pH of 6.5.Under the optimized conditions,the activities of FPU,C1,CMCase and β-glucosidase were 5.25,0.48,19.60 U/mL and 42.86 U/mL,which were 3.0,1.8,2.5 and 2.1 times higher than those before optimization.