Ionic liquid-mediated selective extraction of lignin from wood leading to enhanced enzymatic cellulose hydrolysis

• Published in: Biotechnology and bioengineering Vol. 102; no. 5; pp. 1368 - 1376
• Main Authors: Lee, Sang Hyun, Doherty, Thomas V, Linhardt, Robert J, Dordick, Jonathan S
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01-04-2009; Wiley; Wiley Subscription Services, Inc
• Subjects: Biological and medical sciences; Biotechnology; Biotechnology - methods; Cellulose - metabolism; cellulose crystallinity; Chemical compounds; Chemical reactions; delignification; enzymatic digestibility; Enzymes; Extraction and Processing Industry - methods; Fundamental and applied biological sciences. Psychology; Hydrolysis; Imidazoles - chemistry; ionic liquid; Ions; Lignin - isolation & purification; lignocellulose; Solvents; Solvents - chemistry; Trichoderma - metabolism; Wood; Wood - chemistry; Lignin; cellulose crystallinity; Wood; Cellulose; Delignification; Lignocellulosics; Selectivity; Ionic liquid; enzymatic digestibility; Hydrolysis; Extraction; Digestibility; lignocellulose
• ISSN: 0006-3592; 1097-0290
• DOI: 10.1002/bit.22179

Lignocellulose represents a key sustainable source of biomass for transformation into biofuels and bio-based products. Unfortunately, lignocellulosic biomass is highly recalcitrant to biotransformation, both microbial and enzymatic, which limits its use and prevents economically viable conversion into value-added products. As a result, effective pretreatment strategies are necessary, which invariably involves high energy processing or results in the degradation of key components of lignocellulose. In this work, the ionic liquid, 1-ethyl-3-methylimidazolium acetate ([Emim][CH₃COO]), was used as a pretreatment solvent to extract lignin from wood flour. The cellulose in the pretreated wood flour becomes far less crystalline without undergoing solubilization. When 40% of the lignin was removed, the cellulose crystallinity index dropped below 45, resulting in >90% of the cellulose in wood flour to be hydrolyzed by Trichoderma viride cellulase. [Emim] [CH₃COO] was easily reused, thereby resulting in a highly concentrated solution of chemically unmodified lignin, which may serve as a valuable source of a polyaromatic material as a value-added product. Biotechnol. Bioeng. 2009;102: 1368-1376.