Harnessing cellulolytic potential of a new Aspergillus terreus AP02 strain for developing integrated pre-treatment and saccharification process for efficient lignocellulosic ethanol production

The global need for sustainable energy solutions emphasizes the importance of efficient lignocellulosic biomass conversion into biofuels. In this study, a potent cellulase-producing fungal isolate, Aspergillus terreus AP02, was isolated from rotting wood compost and identified through ITS sequencing and phylogenetic analysis. The crude enzyme extract (AT-CS) obtained from solid-state fermentation displayed a broad enzymatic profile including filter paper activity (1.09 ± 0.067 FPU/ml), CMCase (0.55 ± 0.043 IU/ml), avicellase (0.14 ± 0.009 IU/ml), β-glucosidase (0.45 ± 0.021 IU/ml) and endo-xylanase (8.96 ± 0.77 IU/ml), indicating strong cellulose and hemicellulose degrading potential. An integrated pre-treatment and saccharification (IPS) process was developed using AT-CS and optimized via “One Factor at a Time” (OFAT) approach. Optimal conditions were determined as: 1% (v/v) acid loading, 10% (w/v) biomass loading, 1.0% (w/v) PEG-6000, 45 min pretreatment, 30 FPU/g enzyme dose and 48 hours saccharification time wherein a maximum 0.57 ± 0.016 g/g reducing sugar was released from rice straw. The resulting RS hydrolysate was fermented using Saccharomyces cerevisiae NCIM 3570 and produced 15.82 ± 0.84 g/L ethanol, with 93.93% fermentation efficiency (yield: 0.48 g/g sugar) and 0.659 g/L/h productivity. These findings demonstrated the potential of isolate A. terreus AP02 for cellulolytic enzymes production and feasibility of an optimized IPS strategy for developing agricultural waste based lignocellulosic biorefinery for second-generation bioethanol production.