Recycling enzymatic hydrolysis lignin residues saved cellulase in enzymatic hydrolysis of lignocellulose: An insight from cellulase adsorption mechanism

Enzymatic hydrolysis lignin residues (EHLRs) of lignocellulose usually adsorbs cellulase, which can be recycled and used to replace parts of cellulase in the hydrolysis process. To understand this phenomenon during enzymatic hydrolysis (EH) of sugarcane bagasse (SCB) treated with sulfite (SPORL) and dilute acid (DA), the adsorption characteristics between lignin and cellulase in EHLRs were investigated, focusing on interaction force at molecular level and enzymatic activity. The results revealed that SPORL-EHLR adsorbed more β-glucosidases (β-GLs) through the stronger electrostatic attraction and hydrogen bond force, causing higher cellulase adsorption amount compared to DA-EHLR. Further exploration demonstrated that the cellobiose's catalytic and binding sites on β-GLs were separated from the binding site of SPORL-EHLR on β-GLs, resulting in minimal inhibition of β-GLs activity when bound to SPORL-EHLR. Furthermore, adding SPORL-EHLR in SCB hydrolysis saved 40% cellulase. This study deepens the understanding of the adsorption behavior between lignin and cellulase.