Cellulase production by Aspergillus japonicus URM5620 using waste from castor bean (Ricinus communis L.) under solid-state fermentation.

The activity of β-glucosidase (βG), total cellulase (FPase) and endoglucanase (CMCase), produced by Aspergillus japonicus URM5620, was studied on solid-state fermentation using castor bean meal as substrate. The effect of the substrate amount, initial moisture, pH, and temperature on cellulase production was studied using a full factorial design (2(4)). The maximum βG, FPase, and CMCase activity was 88.3, 953.4, and 191.6 U/g dry substrate, respectively. The best enzyme activities for all three enzymes were obtained at the same conditions with 5.0 g of substrate, initial moisture 15% at 25 °C and pH 6.0 with 120 h of fermentation. The optimum activity for FPase and CMCase was found at pH 3.0 at an optimum temperature of 50 °C for FPase and of 55 °C for CMCase. The cellulases were stable in the range of pH 3.0-10.0 at 50 °C temperature. The enzyme production optimization demonstrated clearly the impact of the process parameters on the yield of the cellulolytic enzymes.