High Production of β-Glucosidase by Aspergillus niger on Corncob

Using low-cost raw material is an effective approach for reducing the cost of cellulolytic enzymes. The farmland waste corncob was found in this study to be the best carbon source for the production of beta-glucosidase by Aspergillus niger. The maximum yield of beta-glucosidase activity was 48.7 IU ml(-1) by using 50 g l(-1) of corncob powder as the substrate. It was found that the water-soluble components of the corncob could increase beta-glucosidase production significantly only when mixed with Avicel or wheat bran. The soluble components could not enhance the biomass and beta-glucosidase production when used alone. On the other hand, the water-insoluble components of the corncob still produced high level of beta-glucosidase (30 IU ml(-1)) although lower than that of using whole corncob. The results suggested that the water-insoluble components of corncob were beneficial for beta-glucosidase production. It was further demonstrated that the xylan in the water-insoluble parts of corncob was the important factor in producing beta-glucosidase by A. niger.