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Title: Understanding Lignin Fractionation and Characterization from Engineered Switchgrass Treated by an Aqueous Ionic Liquid

Abstract

Aqueous ionic liquids (ILs) have received increasing interest because of their high efficacy in fractionating and pretreating lignocellulosic biomass while at the same time mitigating several challenges associated with IL pretreatment such as IL viscosity, gel formation during pretreatment, and the energy consumption and costs associated with IL recycling. This paper investigated the fate of lignin, its structural and compositional changes, and the impact of lignin modification on the deconstruction of cell wall compounds during aqueous IL (10% w/w cholinium lysinate) pretreatment of wild-type and engineered switchgrass. The 4CL genotype resulting from silencing of 4-coumarate:coenzyme A ligase gene (Pv4CL1) had a lower lignin content, relatively higher amount of hydroxycinnamates, and higher S/G ratio and appeared to be less recalcitrant to IL pretreatment likely due to the lower degree of lignin branching and more readily lignin solubilization. The results further demonstrated over 80% of lignin dissolution from switchgrass into the liquid fraction under mild conditions while the remaining solids were highly digestible by cellulases. The soluble lignin underwent partial depolymerization to a molecular weight around 500–1000 Da. 1H– 13C HSQC NMR results demonstrated that the variations in lignin compositions led to different modes of lignin dissolution and depolymerization during pretreatment ofmore » engineered switchgrass. Finally, these results provide insights into the impact of lignin manipulation on biomass fractionation and lignin depolymerization and lead to possible ways toward developing a more selective and efficient lignin valorization process based on aqueous IL pretreatment technology.« less

Authors:
 [1];  [2];  [1];  [2];  [3];  [3];  [4]; ORCiD logo [5]; ORCiD logo [1]
  1. Univ. of Kentucky, Lexington, KY (United States). Biosystems and Agricultural Engineering
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Joint Inst. of Biological Science. Center for BioEnergy Innovation. Biosciences Division
  3. Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States). Dept. of Horticulture
  4. Univ. of Kentucky, Lexington, KY (United States). Center for Applied Energy Research. Dept. of Chemistry
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Joint Inst. of Biological Science. Center for BioEnergy Innovation. Biosciences Division; Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemical & Biomolecular Engineering. Center for Renewable Carbon. Dept. of Forestry, Wildlife, and Fisheries
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Kentucky, Lexington, KY (United States); Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); National Science Foundation (NSF); USDA National Inst. of Food and Agriculture (NIFA); Virginia Polytechnic Inst. and State Univ. (Virginia Tech) (United States)
OSTI Identifier:
1468147
Grant/Contract Number:  
AC05-00OR22725; 1355438; 1632854; 2011-67009-30133; VA135872
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
ACS Sustainable Chemistry & Engineering
Additional Journal Information:
Journal Volume: 6; Journal Issue: 5; Journal ID: ISSN 2168-0485
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; engineered switchgrass; ionic liquid; lignin; pretreatment

Citation Formats

Liu, Enshi, Li, Mi, Das, Lalitendu, Pu, Yunqiao, Frazier, Taylor, Zhao, Bingyu, Crocker, Mark, Ragauskas, Arthur J., and Shi, Jian. Understanding Lignin Fractionation and Characterization from Engineered Switchgrass Treated by an Aqueous Ionic Liquid. United States: N. p., 2018. Web. doi:10.1021/acssuschemeng.8b00384.
Liu, Enshi, Li, Mi, Das, Lalitendu, Pu, Yunqiao, Frazier, Taylor, Zhao, Bingyu, Crocker, Mark, Ragauskas, Arthur J., & Shi, Jian. Understanding Lignin Fractionation and Characterization from Engineered Switchgrass Treated by an Aqueous Ionic Liquid. United States. doi:10.1021/acssuschemeng.8b00384.
Liu, Enshi, Li, Mi, Das, Lalitendu, Pu, Yunqiao, Frazier, Taylor, Zhao, Bingyu, Crocker, Mark, Ragauskas, Arthur J., and Shi, Jian. Fri . "Understanding Lignin Fractionation and Characterization from Engineered Switchgrass Treated by an Aqueous Ionic Liquid". United States. doi:10.1021/acssuschemeng.8b00384. https://www.osti.gov/servlets/purl/1468147.
@article{osti_1468147,
title = {Understanding Lignin Fractionation and Characterization from Engineered Switchgrass Treated by an Aqueous Ionic Liquid},
author = {Liu, Enshi and Li, Mi and Das, Lalitendu and Pu, Yunqiao and Frazier, Taylor and Zhao, Bingyu and Crocker, Mark and Ragauskas, Arthur J. and Shi, Jian},
abstractNote = {Aqueous ionic liquids (ILs) have received increasing interest because of their high efficacy in fractionating and pretreating lignocellulosic biomass while at the same time mitigating several challenges associated with IL pretreatment such as IL viscosity, gel formation during pretreatment, and the energy consumption and costs associated with IL recycling. This paper investigated the fate of lignin, its structural and compositional changes, and the impact of lignin modification on the deconstruction of cell wall compounds during aqueous IL (10% w/w cholinium lysinate) pretreatment of wild-type and engineered switchgrass. The 4CL genotype resulting from silencing of 4-coumarate:coenzyme A ligase gene (Pv4CL1) had a lower lignin content, relatively higher amount of hydroxycinnamates, and higher S/G ratio and appeared to be less recalcitrant to IL pretreatment likely due to the lower degree of lignin branching and more readily lignin solubilization. The results further demonstrated over 80% of lignin dissolution from switchgrass into the liquid fraction under mild conditions while the remaining solids were highly digestible by cellulases. The soluble lignin underwent partial depolymerization to a molecular weight around 500–1000 Da. 1H–13C HSQC NMR results demonstrated that the variations in lignin compositions led to different modes of lignin dissolution and depolymerization during pretreatment of engineered switchgrass. Finally, these results provide insights into the impact of lignin manipulation on biomass fractionation and lignin depolymerization and lead to possible ways toward developing a more selective and efficient lignin valorization process based on aqueous IL pretreatment technology.},
doi = {10.1021/acssuschemeng.8b00384},
journal = {ACS Sustainable Chemistry & Engineering},
issn = {2168-0485},
number = 5,
volume = 6,
place = {United States},
year = {2018},
month = {3}
}

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