The Role of Polymeric Micelles on Chemical Changes of Pretreated Corn Stover,Cellulase Structure,and Adsorption

Enzymatic hydrolysis of lignocellulosic biomass is limited by rapid cellulase deactivation, consequently requiring large amounts of enzyme to maintain acceptable biomass conversion. In this study, a new approach to improve lignocellulose hydrolysis was investigated. Performing enzymatic hydrolysis of corn stover (CS) in the presence of polymeric–surfactant micelles (PMs) was demonstrated to improve hydrolysis yield to a greater extent than using only surfactant micelles. Application of 2 % (w/w) of polyethylene glycol (PEG 6000) with casein, Tween-20, and Triton X-100 at levels above the critical micelle concentrations increased the hydrolysis yield of CS containing high-bound lignin (extrusion-pretreated) by up to 87.8, 11.7, and 7.5 %, respectively. These PMs were not effective during enzymatic hydrolysis of biomass lacking lignin (Avicel) or alkali-pretreated CS (7.2 % lignin). The main reasons for the enhanced cellulase activity observed due to PEG-casein, PEG-Tween, and PEG-Triton were enhanced cellulase solubilization; reformation of α-helix substructure; and combination of induced cellulase solubilization, α-helix reformation, and chemical changes in the microstructure of biomass, respectively. Deformation of the cellulase substructure during hydrolysis of biomass and its subsequent reformation in the presence of surfactants were shown in this study for the first time. Chemical changes in the microstructure of biomass (e.g., lignin side changes, C–O bonds, and amorphous cellulose) were found to be another potential reason for the effectiveness of surfactants when they are incubated at above 6 g/L for 72 h with biomass.