(519g) Lignin-Based Deep Eutectic Solvent Pretreatment of Transgenic Sweet Sorghum Bagasse to Achieve a Sustainable Biorefinery Process

Conversion efficiency is one of technical and economic obstacles in lignocellulosic biomass utilization. In this study, a closed-loop process with lignin-derived deep eutectic solvent (DES) pretreatment and genetically modified p­-Hydroxybenzoic acid (PB)-rich sweet sorghum bagasse was investigated. DES synthesized with choline chloride (ChCl) and PB has shown high pretreatment efficiency. Results show that ChCl-PB DES effectively fractionated both wild-type and transgenic sweet sorghum bagasse at mild temperatures. The cellulase accessibility was significantly improved after the pretreatment. Formation of aqueous DES with a small quantity of water enhanced its pretreatment performance further. Recovered lignin was characterized with two-dimensional heteronuclear single quantum coherence (2D HSQC) nuclear magnetic resonance (NMR), ³¹P NMR, and gel permeation chromatography (GPC) to understand the interaction between DES and biomass. The pretreatment preserved about half of the amount of β-O-4 linkage with relatively uniform sizes and low molecular weight. No condensed lignin unit was observed. This study indicates that the integration of lignin-based DES with genetic engineering is a promising strategy to develop a sustainable biorefinery process.