Sustainable Valorization of Coffee Husk for Fungal Cellulase Production and Biomass Saccharification

ABSTRACT Cellulases are essential enzymes for breaking down lignocellulosic biomass in second‐generation ethanol production, but their high cost limits widespread use. Solid‐state fermentation (SSF) offers a cost‐effective alternative by producing high enzyme yields from agro‐industrial residues. This study investigated cellulase production by Aspergillus fumigatus using coffee husks, both untreated and pretreated via combined alkaline and microwave methods, as carbon sources. The effects of initial moisture (50%–70%) and husk content (60%–80%) on SSF were optimized through response surface methodology. The crude enzymatic extract was biochemically characterized for optimal pH (3–8), temperature (30–70°C), thermal stability, and metal ion effects. Pretreated husks increased enzyme activity (FPase) by 121%, confirming improved cellulose accessibility. The extract showed optimal activity at pH 5–6, stability between 40°C and 60°C, and enhanced performance with Cu 2 + , Co 2 + , and Mn 2 + . When applied to hydrolysis of pretreated coffee husks, the extract achieved 27 mg/g conversion after 48 h, demonstrating its effectiveness. These results indicate that coffee husk serves both as an inducer of fungal cellulase production and as a lignocellulosic feedstock, emphasizing its biotechnological potential for sustainable biomass valorization.