Bioprospecting CAZymes repertoire of Aspergillus fumigatus for eco-friendly value-added transformations of agro-forest biomass

Abstract

Background: Valorizing waste residues is crucial to reaching sustainable development goals and shifting from a linear fossil-based economy to a circular economy. Fungal cell factories, due to their versatility and robustness, are instrumental in driving the bio-transformation of waste residues. The present work isolated a potent strain, i.e., Aspergillus fumigatus (ZS_AF), from an ancient Złoty Stok gold mine, which showcased distinctive capabilities for efficient hydrolytic enzyme production from lignocellulosic wastes. Results: The present study optimized hydrolytic enzyme production (cellulases, xylanases, and β-glucosidases) from pine sawdust (PSD) via solid-state fermentation using Aspergillus fumigatus (ZS_AF). The optimization, using response surface methodology (RSM), produced a twofold increase with maximal yields of 119.41 IU/gds for CMCase, 1232.23 IU/gds for xylanase, 63.19 IU/gds for β-glucosidase, and 31.08 IU/gds for FPase. The secretome profiling validated the pivotal role of carbohydrate-active enzymes (CAZymes) and auxiliary enzymes in biomass valorization. A total of 77% of carbohydrate-active enzymes (CAZymes) were constituted by glycoside hydrolases (66%), carbohydrate esterases (9%), auxiliary activities (3%), and polysaccharide lyases (3%). The saccharification of pretreated wheat straw and PSD generated high reducing sugar yields of 675.36 mg/g and 410.15 mg/g, respectively. Conclusion: These findings highlight the significance of an efficient, synergistic, and cost-effective arsenal of fungal enzymes for lignocellulosic waste valorization and their potential to contribute to waste-to-wealth creation through solid-waste management. The utilization of Aspergillus fumigatus (ZS_AF) from an unconventional origin and optimization strategies embodies an innovative approach that holds the potential to propel current waste valorization methods forward, directing the paradigm toward improved efficiency and sustainability.