title: An In-Depth Understanding of Biomass Recalcitrance Using Natural Poplar Variants as the Feedstock.
abstract: In an effort to better understand the biomass recalcitrance, six natural poplar variants were selected as feedstocks based on previous sugar release analysis. Compositional analysis and physicochemical characterizations of these poplars were performed and the correlations between these physicochemical properties and enzymatic hydrolysis yield were investigated. Gel permeation chromatography (GPC) and13C  solid state NMR were used to determine the degree of polymerization (DP) and crystallinity index (CrI) of cellulose, and the results along with the sugar release study indicated that cellulose DP likely played a more important role in enzymatic hydrolysis. Simons' stain revealed that the accessible surface area of substrate significantly varied among these variants from 17.3 to 33.2 mg g-1biomass as reflected by dye adsorption, and cellulose accessibility was shown as one of the major factors governing substrates digestibility. HSQC and31P NMR analysis detailed the structural features of poplar lignin variants. Overall, cellulose relevant factors appeared to have a stronger correlation with glucose release, if any, than lignin structural features. Lignin structural features, such as a phenolic hydroxyl group and the ratio of syringyl and guaiacyl (S/G), were found to have a more convincing impact on xylose release. Low lignin content, low cellulose DP, and high cellulose accessibility generally favor enzymatic hydrolysis; however, recalcitrance cannot be simply judged on any single substrate factor.
authors.affiliation: Department of Chemical & Biomolecular Engineering, University of Tennessee Knoxville, Knoxville, TN, 37996, USA.
authors.forename: Xianzhi
authors.initials: X
authors.lastname: Meng
authors.affiliation: BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.|Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
authors.forename: Yunqiao
authors.initials: Y
authors.lastname: Pu
authors.affiliation: BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.|Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
authors.forename: Chang Geun
authors.initials: CG
authors.lastname: Yoo
authors.affiliation: BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.|Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
authors.forename: Mi
authors.initials: M
authors.lastname: Li
authors.affiliation: Renewable Bioproducts Institute, School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332, USA.
authors.forename: Garima
authors.initials: G
authors.lastname: Bali
authors.affiliation: Renewable Bioproducts Institute, School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332, USA.
authors.forename: Doh-Yeon
authors.initials: DY
authors.lastname: Park
authors.affiliation: BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.|National Renewable Energy Laboratory, Golden, CO, 80401, USA.
authors.forename: Erica
authors.initials: E
authors.lastname: Gjersing
authors.affiliation: BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.|National Renewable Energy Laboratory, Golden, CO, 80401, USA.
authors.forename: Mark F
authors.initials: MF
authors.lastname: Davis
authors.affiliation: BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.|Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
authors.forename: Wellington
authors.initials: W
authors.lastname: Muchero
authors.affiliation: BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.|Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
authors.forename: Gerald A
authors.initials: GA
authors.lastname: Tuskan
authors.affiliation: BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.|Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Tschaplinski
authors.affiliation: Department of Chemical & Biomolecular Engineering, University of Tennessee Knoxville, Knoxville, TN, 37996, USA.|BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.|Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.|Center for Renewable Carbon, Department of Forestry, Wildlife, and Fisheries, University Tennessee Institute of Agriculture, Knoxville, TN, 37996, USA.
authors.forename: Arthur J
authors.identifier: http://orcid.org/0000-0003-1420-6678
authors.initials: AJ
authors.lastname: Ragauskas
mesh_terms: D056804:Biofuels; D018533:Biomass; D001709:Biotechnology; D002482:Cellulose / Q000737:chemistry; D006868:Hydrolysis; D008031:Lignin / Q000737:chemistry; D058105:Polymerization; D032107:Populus / Q000737:chemistry* / Q000254:growth & development
chemical_list: D056804:Biofuels; D002482:Cellulose; D008031:Lignin
keywords: biomass recalcitrance; cellulose; crystallinity; degree of polymerization; lignin