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

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 L^-1 of 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^-1. 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 CaCl₂ (60.5% increase at 5 mM) and strongly inhibited by FeSO₄, 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.