Sustainable Bioprocessing of Invasive Water Hyacinth: Aspergillus -Derived Cellulase for Industrial Applications

Abstract

The rapid spread of the invasive aquatic plant Eichhornia crassipes (water hyacinth [WH]) poses serious ecological and environmental challenges. This study explores the potential valorization of WH biomass by using the fungus Aspergillus niger to produce filter paperase (FPase). A classical screening approach was followed by optimization using response surface methodology with a central composite design (CCD) via Stat-Ease 360 software. Incubation time, pH, and lactose concentration were selected as key parameters for optimization. Maximum FPase activity (4.10 U/mL) was achieved under conditions of 6 days incubation, pH 5.5, and 1.25% (w/v) lactose. To enhance enzyme accessibility, the biomass was pretreated using steam-assisted NaOH, resulting in substantial compositional changes: cellulose content increased by 41.67%, while lignin and hemicellulose decreased by 58.71% and 11.74%, respectively. The highest fermentable sugar yield (0.294 ± 0.04 g/g) was obtained after 96 hours of enzymatic hydrolysis using 30 FPU/100 mL of FPase and 3% (w/v) substrate loading. These results highlight the dual benefit of converting an environmental nuisance into a valuable resource. WH-derived FPase shows significant promise for applications in bioethanol production, biomass valorization, and integrated biorefinery systems. Moreover, this work suggests a sustainable and eco-friendly approach to managing invasive aquatic weeds through microbial bioconversion.