β-glucosidase production of two different Aspergillus strains

P-Glucosidase has an important role in cellulose degradation by cleaving the cellobiose to glucose units. Supplementation of Trichoderma cellulase with exogenous beta-glucosidase is needed to prevent the inhibition effect of cellobiose on exoglucanases and endoglucanases. Production of beta-glucosidase by Aspergillus niger and Aspergillus phoenicis has been investigated under different fermentations. Both strains were appropriate for enzyme production at high level under the applied conditions. Cultivation of A. phoenicis on Mandels' medium containing a complex nitrogen source has resulted in a higher beta-glucosidase activity than on Vogel's medium. In an air-lift fermenter A. phoenicis grew in the shape of beads with 1.41 IU g(-1) cell-associated enzyme activity. The fungal pellets can be used as in situ immobilized enzyme preparation. A. niger produced extracellular beta-glucosidase at the level of 2.1 IU ml(-1) in stirred-tank fermenter with a yield of 210 IU g(-1) glucose and productivity of 21.8 IU l(-1) h(-1).