Synergistic Multi-Enzyme Engineering Enhances Glucose and Xylose Production from Alkali-Pretreated Sugarcane Bagasse

Abstract

This study investigates the conversion of sugarcane bagasse into fermentable sugars through an integrated alkaline pretreatment and synergistic enzymatic hydrolysis strategy. Dilute NaOH pretreatment (1% NaOH, 150°C, 60 min) effectively modified biomass structure, achieving approximately 59% lignin removal and 69.6% deacetylation while preserving cellulose (1.2% loss). These structural modifications enriched cellulose content to 54.2% and significantly improved substrate accessibility. Subsequent hydrolysis using a strategically formulated full enzyme cocktail (Cellulase + β-glucosidase + xylanase + acetyl esterase) exhibited pronounced synergistic effects, achieving near-complete polysaccharide conversion (97.4% glucan and 91.2% xylan at 72h). Total sugar production reached 38.4 g/L, representing a 140% increase compared with cellulase alone. Strong early-stage synergy was observed within 24h (150% sugar yield), with synergy index values greater than unity confirming cooperative interactions beyond additive effects. Mechanistic analysis indicates that coordinated hemicellulose backbone cleavage and enzymatic deacetylation play a more decisive role in enhancing hydrolysis efficiency than product inhibition relief alone. These findings demonstrate that integrating selective alkaline pretreatment with rational enzyme system design effectively overcomes biomass recalcitrance and provides a promising approach for improving the efficiency and industrial feasibility of second-generation bioethanol production.