Production of β-glucosidase by the space mutant strain Aspergillus niger ZM-8 on solid fermentation

Using wheat stalk and wheat bran as materials,the conditions for the producing of β-glucosidase by the space mutant strain Aspergillus niger ZM-8 on solid was studied.The results indicated that the optimum components of medium for β-glucosidase production were as follows:the mass ratio for wheat stalk and wheat bran was 8∶2,the nitrogen source was(NH4)2SO4 and its content was 4 %,the water content was 200 %.The optimum culture conditions were as follow:the inoculation amount was 6 %,the initial pH was 6.5,the culture temperature was 28 ℃ and the culture time was 144 hours.Under above medium and conditions,the enzyme activity of β-glucosidase was 21.74 U/g and increased by 2.24 times as compared with the parent strain.The results of enzymology characteristic demonstrated that the optimum temperature was 50 ℃ and the optimum pH was 5.0.