Production and optimization of β-glucosidase by Penicillium chrysogenium under solid-state fermentation using response surface methodology

Abstract

Conversion of waste to wealth has been described as critical to development and advancement of economic gains of a country. This study was aimed at the production and optimization of β-glucosidase by Penicillium chrysogenium using agro waste as substrate under solid state fermentation. Wheat bran and corn cob used as substrates was analysed for proximate analysis to study the effect of pre-treatments on crude protein, fibre, ash, total available carbohydrates, moisture content, hemicellulose and lignin concentration. Soil samples were obtained using surficial soil (0 - 15 cm) by an auger, from different dumpsites in Port Harcourt. A total of 8 fungal isolates were isolated from the 5 different dumpsites. Total fungal count ranged from 3.2 x 10⁴ - 1.2 x 10⁸ CFU/g with M1M₁ exhibiting the highest preponderance and was selected for further study. The fungal isolate was identified as Penicillium chrysogenium using morphological and biochemical characteristics. A response surface methodology (RSM) involving Box-Behnken design (BBD) was used to investigate the interaction between variables (pH, temperature, wheat bran concentration and incubation time) that influence β-glucosidase production. Assessment of lignocellulose wastes for enzyme production revealed wheat bran to be most effective substrate for β-glucosidase production by the fungus under solid state fermentation with enzyme activity of 11.21 IU/ml. The application of RSM involving BBD showed that maximum enzyme activity (11.21 IU/ml) was achieved at pH 5.0, temperature 30^oC using 40 % wheat bran as the best carbon source after 108 h of fermentation. The models developed using RSM were significant at p<0.001 and multiple correlation co-efficient (R² ) was 0.71 for the enzyme. Thus, indicating correlations between the various process parameters for β-glucosidase production by Penicillium chrysogenium under solid state fermentation. Microbial enzyme production in Nigeria, if adequately documented can create a greener bioeconomy, provide sustainable jobs and revenue.