Integrated Nondestructive Spectroscopic Technology to Reveal the Influence Mechanism of Lignins from Pretreated Corn Stover on Cellulose Saccharification

Abstract

The changes in the structure of lignin during the pretreatment processes of biomass can affect its subsequent enzymatic hydrolysis efficiency. To explore the influence mechanism of dilute acid and hydrothermal pretreatment of corn stover lignin on cellulose saccharification, an integrated nondestructive spectral technology with fluorescence spectroscopy, surface plasmon resonance, and atomic force microscopy was performed. It showed that the surface lignins on the corn stover with dilute acid pretreatment at 190 °C (DA190-SL) and hydrothermal pretreatment at 190 °C (HP190-SL) possessed enhancement (from 76.95 to 80.09%) and inhibition (from 76.95 to 61.91%) for the enzymatic digestibility of Avicel, respectively. Nondestructive spectroscopic analysis indicated that HP190-SL adsorbed onto cellulase is mainly driven by hydrogen bonding and van der Waals forces, while the DA190-SL-enzyme system was mainly driven by hydrophobic interactions. The association affinity of DA190-SL combined with cellulase was higher than that of HP190-SL. The binding force of the HP190-SL-enzyme (0.16 nN) is lower than that of the DA190-SL-enzyme (0.75 nN), which leads to a higher propensity for dissociation of HP190-SL from cellulase after binding. This study aims to establish a theoretical basis for regulating the enzymatic performance during the hydrothermal and dilute acid pretreatment of corn stover at the molecular level.