Isolation, screening wood rot fungi from the tropical forest of Thailand and their lignocellulolytic enzyme production under solid-state fermentation using agricultural waste as substrate

The present study aimed to discover good lignocellulolytic enzyme (LCE) producers from Thailand's tropical forest and then examine their multiple LCE production (including carboxymethyl cellulase (CMCase), xylanase, and laccase) using agricultural wastes as substrate. The total collection was 50 fungi, mainly from the Polyporales, Agaricales, and Xylariales orders. During primary screening by qualitative method and secondary screening by quantitative method, two potential fungi were proposed for multiple LCE production, including Auricularia auricula-judae 088 and Pseudolagarobasidium acaciicola TDW-48. Under solid-state fermentation (SSF) using agricultural wastes as substrates, P. acaciicola TDW-48 performed as a good producer that highly secreted simultaneous CMCase, xylanase, and laccase. In the next stage, the simplex lattice mixture design assessed the interaction of agricultural waste substrates and their effects on P. acaciicola TDW-48's enzyme production. The results indicated that agricultural waste has different influences on CMCase, xylanase, and laccase production: orange peel showed a positive effect on both CMCase and xylanase activity, but a negative effect on laccase. In contrast, wheat bran positively influenced laccase, while it limited CMCase and xylanase. However, the combination of these substrates in the mixture showed synergic effects and improved enzyme activity. Through numerical optimization, a ternary mixture of wheat bran (1.27 g), orange peel (1.53 g), and rice husk (0.2 g) was identified as the most appropriate formulation for simultaneous multiple LCE production, reaching 20.96 U/g substrate for CMCase, 23.94 U/g substrate for xylanase, and 27.55 U/g substrate for laccase. These results provided a promising candidate for LCE production with high applicability in lignocellulose bioconversion and successfully demonstrated the relationship between the agricultural waste substrate and multiple LCE production that supported the enzyme production following the environmentally friendly and economical approach.