Optimization of Cellulase Production by Daldinia concentrica through Variation of Incubation Time and Lignocellulosic Substrate under Solid-State Fermentation

Abstract

A significant portion of agricultural and industrial by-products, such as sugarcane bagasse, rice husks, and eucalyptus sawdust, are underutilised despite their potential as abundant sources of cellulose. Fungal species are excellent producers of cellulases that hydrolyze cellulose into fermentable sugars for various industrial applications. This study optimised cellulase production by Daldinia concentrica through variation of incubation time and lignocellulosic substrates under solid-state fermentation (SSF). A confirmed Daldinia concentrica culture was grown on untreated sugarcane bagasse, rice husks, and eucalyptus sawdust using Bushnell-Haas medium, a mineral salt medium providing essential nutrients (Mg²⁺, Fe²⁺, K⁺, and trace elements) that act as enzyme cofactors, supporting fungal metabolism, and moisture for fungal growth. Enzyme activities (FPase, endoglucanase, and exoglucanase) were measured every two days for ten days. Statistical analysis using one-way ANOVA (R v4.5.0) and Tukey’s post hoc test (p ≤ 0.05) revealed significant effects of both substrate type and incubation period on enzyme yield. The results showed maximum FPase activity (2.41 ± 0.08 IU/mL) on rice husks at day 6, the highest endoglucanase (4.77 ± 0.11 IU/mL) on sugarcane bagasse after eight days, and the highest exoglucanase (1.43 ± 0.04 IU/mL) was observed on eucalyptus sawdust after eight days. These findings suggest that Daldinia concentrica is a promising cellulase producer, and scaling up could offer a cost-effective approach for agro-waste valorization.