A New Combinational Statistical Approach for Cellulase Optimization in Aspergillus nidulans

The enhancement of the cellulase activity of Aspergillus nidulans by combinational optimization technique was investigated. The strain isolated from decayed, dry leaf of Ficus caricus was compared for the first time for its ability to produce cellulolytic enzyme in submerged fermentation (SmF). The medium ingredients enhancing the cellulase production were optimized by combinational statistical approach by one factor at a time methodology (OFAT), Plackett Burmann methodology (PB) and response surface methodology (RSM). A four-factor-five-level central composite design (CCD) was employed to determine the maximum activity of cellulase at optimum levels of carboxy methyl cellulose (CMC), ammonium nitrate and potassium dihydrogen phosphate at varying pH values. The optimum fermentation parameters were found to be 1.2 g/l CMC, 0.9 mg/l ammonium nitrate and 0.75 mg/l potassium dihydrogen phosphate at pH 6. The optimization of medium by combinational statistical approach led to the fine tuning of the cellulase production thereby enhancing the cellulase activity from 4.91 U/ml to 39.56 U/ml. The predicted results were in agreement with the actual experimental values. The cellulase activity obtained with this strain may be one of the best obtained in Aspergillus nidulans.