Cellulase with high β-glucosidase activity by Penicillium oxalicum under solid state fermentation and its use in hydrolysis of cassava residue

Abstract

In this study, we investigated cellulase production by Penicillium oxalicum EU2106 under solid-state fermentation (SSF) and its hydrolysis efficiency toward NaOH-H₂O₂-pretreated cassava residue (NHCR) produced after bioethanol fermentation. Optimization of SSF cultivation conditions for P. oxalicum EU2106 using a Box-behnken design-based response-surface methodology resulted in maximal cellulase activity of 34.0 ± 2.8 filter-paper units/g dry substrate, exhibiting a ~ twofold increase relative to activities obtained under non-optimized conditions. Furthermore, SSF-derived cellulase converted 94.3 ± 1.5% of NHCR cellulose into glucose within 96 h. Interestingly, P. oxalicum EU2106 produced higher β-glucosidase activity under SSF conditions than that under submerged-state fermentation conditions, resulting in the elimination of cellobiose inhibition during the early stages of NHCR cellulose hydrolysis. Overall, this work provided an alternative for a potential cellulase source and a preferred option for cassava residue biotechnological application.

Keywords: Cassava residue; Cellulase; Hydrolysis efficiency; Penicillium oxalicum; Solid-state fermentation.