This study was aimed to evaluate the pattern of cellulase biosynthesis from Aspergillus fumigatus ABK9 under submerged fermentation. Production was increased concomitantly with fungal growth up to 72 h and reached maximum (Xmax –6.72 g/l) with specific growth rate (µmax) of 0.126/h. Highest specific rate of enzyme production (qp) was found at initial medium pH of 5.0 and incubation temperature of 30°C. At the same time, in the presence of 2-deoxy-D-glucose concentration of 0.5 mg/ml, the production of cellulolytic enzymes, viz, carboxymethyl cellulase activity (CMCase), filter paper degrading activity (FPase) and β-glucosidase activity reached maximum of 132.2, 21.3 and 28.9 U/ml, respectively. Cellulase biosynthesis was induced in respect to higher volumetric production rate (Qp), specific rate of enzymes production (qp, U/g biomass/h) and enzyme/biomass yield (YE/X) when grown in carboxymethyl cellulose in comparison to other saccharides as sole carbon source. Induction ratios (IR) of cellulases were between 12.3 and 24.4 in the presence of 1.5% (w/v) CMC in the culture media. The strain was quite resistant to catabolic repression by glucose up to 0.4% (w/v). Cellulases production was greatly influenced in the presence of yeast extract and potassium dihydrogen phosphate (KH₂PO₄) as nitrogen and phosphate sources in the culture media. C/N ratio of 10.0 and C/P ratio of 4.0 proved to be the best for the production of enzyme cocktail. Along with the high production yield, the crude enzymes showed a promising cellulose hydrolyzing efficiency of rice straw, indicating the enzyme could be beneficial for its large scale industrial exploitation.
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