Laccase production by a new isolate of Irpex cf. latemarginatus using cocoa (Theobroma cacao) husk waste as substrate under solid state fermentation

This study investigates the production and biochemical characterization of laccase from the white-rot fungus Irpex cf. latemarginatus using agro-industrial waste under solid-state fermentation. Cocoa husk waste was identified as the most suitable substrate, and sterile tap water as the optimal moisture-adjusting agent, yielding 4.4 U Lof laccase activity. Box-Behnken optimization approach revealed that supplementation with 30% cocoa bean shell significantly enhanced enzyme production, resulting in a 12.5-fold increase and a maximum activity of approximately 55 U L. The crude enzyme preparation with laccase activity exhibited maximum activity at pH 4.0 and 60 °C, while greater thermal stability was observed at pH 5.0 and 40 °C, retaining 55% of its initial activity after 4 h. Enzyme activity was enhanced by CaCl(60.5% increase at 5 mM) and strongly inhibited by FeSO, SDS and β-mercaptoethanol. These findings expand current knowledge of laccase production within the underexplored genus Irpex and contribute to the evaluation of cocoa-derived residues as low-cost substrates for enzyme production.