Potential of peanut hulls as substrates for fungal cellulase bioproduction through solid state fermentation

Abstract

One of the main challenges of cellulosic bio-ethanol production is the cellulase enzyme. Cellulase is used in the hydrolysis of cellulose to sugars for the fermentation of bio-ethanol, but the commercial cellulase enzyme preparations are very expensive. This study has attempted to use peanut hulls as a substrate for cellulase production via solid-state fermentation (SSF) by white-rot fungus, Ganoderma australe. The effects of moisture content, culture temperature and initial pH value on cellulase biosynthesis were observed for optimal production in flask fermentors. The activities of different cellulase enzymes, namely filter paper activity (FPAse), carboxymethyl cellulase (CMCase) and?-Glucosidase (cellobiase) were carried out using filter paper, carboxymethylcellulose and cellobiose as the substrate, repectively. The optimal FPAse activity (0.062?0.017 IU/ml), CMCase activity (0.426?0.074 IU/ml) and cellobiase activity (0.035?0.007 IU/ml), were obtained after 9 days of cultivation with an initial 70% of moisture content, a temperature of 25oC and an initial pH of 5.5. These results suggest that the crude cellulase production under SSF using peanut hulls as a substrate could be an alternative choice for commercial enzyme preparations.