Optimization of Cellulase Activity by Aspergillus niger and Penicillium chrysogenum using Some Agricultural Wastes

Abstract

Cellulases are enzymes widely used in various manufacturing processes, yet their production faces challenges such as the high cost of raw materials, low product recovery due to microbial cell characteristics, and unfavorable growth conditions, all of which lead to increased costs of finished products. This study aimed to investigate the optimum physicochemical conditions that could enhance cellulase production by Aspergillus niger and Penicillium chrysogenum using agricultural wastes as substrates. Each fungal species was grown in a mineral salt medium containing paper, sugarcane bagasse, or wheat bran as the sole carbon source at various concentrations. Cellulase activity was found to be optimum at 5% w/v substrate concentration after 96 hours of incubation. Wheat bran supported the highest cellulase activity (5.36 IU for A. niger and 3.62 IU for P. chrysogenum) at pH 5 and a temperature of 30°C. In contrast, using paper as a substrate, the optimum enzyme activity was observed at pH 6, with a temperature range of 35°C for A. niger and 45°C for P. chrysogenum (1.28 IU and 1.26 IU, respectively). For sugarcane bagasse, the optimum pH for cellulase activity was 5, with P. chrysogenum showing higher activity (1.01 IU) at 40°C compared to A. niger (0.91 IU) at 50°C. However, cellulase activity using paper and sugarcane bagasse was significantly lower (p<0.05) than with wheat bran under these conditions. This study revealed that A. niger and P. chrysogenum are excellent cellulase producers under optimal conditions of 30°C and pH 5, using wheat bran at 5% concentration. These findings highlight their potential for large-scale cellulase production.