Insights into the mechanism of lignin–cellulase interactions during kraft pretreatment of larch

Understanding the impact of lignin structural changes on cellulase adsorption is key to revealing its inhibitory role in enzymatic hydrolysis. In this study, kraft pretreatment was applied to larch to investigate its impact on enzymatic hydrolysis performance and lignin-cellulase adsorption effects. Under severe conditions (180 °C) with 80.9% delignification, the enzymatic hydrolysis yield was only 35.9%, but improved to 60.9% upon mitigating non-productive lignin adsorption using BSA. NMR analysis revealed that kraft pretreatment significantly enhanced lignin depolymerization and condensation, resulting in reduced molecular weight, increased hydrophobicity, and a more negative zeta potential. SPR (Surface Plasmon Resonance) and FLS (Fluorescence Spectroscopy) results revealed that hydrophobic interactions predominantly drive the binding of residual lignin to cellulase by promoting stronger association and reduced dissociation. This study provides insights into non-productive adsorption mechanisms of lignin-cellulase, and contributes to strategies for improving fermentable sugar production from larch.