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Title: Visualizing chemical functionality in plant cell walls

Abstract

Understanding plant cell wall cross-linking chemistry and polymeric architecture is key to the efficient utilization of biomass in all prospects from rational genetic modification to downstream chemical and biological conversion to produce fuels and value chemicals. In fact, the bulk properties of cell wall recalcitrance are collectively determined by its chemical features over a wide range of length scales from tissue, cellular to polymeric architectures. Microscopic visualization of cell walls from the nanometer to the micrometer scale offers an in situ approach to study their chemical functionality considering its spatial and chemical complexity, particularly the capabilities of characterizing biomass non-destructively and in real-time during conversion processes. Microscopic characterization has revealed heterogeneity in the distribution of chemical features, which would otherwise be hidden in bulk analysis. Key microscopic features include cell wall type, wall layering, and wall composition - especially cellulose and lignin distributions. Microscopic tools, such as atomic force microscopy, stimulated Raman scattering microscopy, and fluorescence microscopy, have been applied to investigations of cell wall structure and chemistry from the native wall to wall treated by thermal chemical pretreatment and enzymatic hydrolysis. While advancing our current understanding of plant cell wall recalcitrance and deconstruction, microscopic tools with improved spatial resolutionmore » will steadily enhance our fundamental understanding of cell wall function.« less

Authors:
ORCiD logo [1];  [1];  [2]
  1. National Renewable Energy Lab. (NREL), Golden, CO (United States). Biosciences Center; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). BioEnergy Science Center (BESC)
  2. Michigan State Univ., East Lansing, MI (United States). Department of Plant Biology
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
OSTI Identifier:
1416720
Report Number(s):
NREL/JA-2700-70484
Journal ID: ISSN 1754-6834
Grant/Contract Number:
AC36-08GO28308; FC02-07ER64494
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Biotechnology for Biofuels
Additional Journal Information:
Journal Volume: 10; Journal Issue: 1; Journal ID: ISSN 1754-6834
Publisher:
BioMed Central
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; 59 BASIC BIOLOGICAL SCIENCES; plant cell wall; cell wall imaging; biomass recalcitrance; bioenergy; lignocellulosic biomass; stimulated raman scattering; atomic force microscopy; fluorescence; fluorescence lifetime imaging microscopy

Citation Formats

Zeng, Yining, Himmel, Michael E., and Ding, Shi-You. Visualizing chemical functionality in plant cell walls. United States: N. p., 2017. Web. doi:10.1186/s13068-017-0953-3.
Zeng, Yining, Himmel, Michael E., & Ding, Shi-You. Visualizing chemical functionality in plant cell walls. United States. doi:10.1186/s13068-017-0953-3.
Zeng, Yining, Himmel, Michael E., and Ding, Shi-You. 2017. "Visualizing chemical functionality in plant cell walls". United States. doi:10.1186/s13068-017-0953-3. https://www.osti.gov/servlets/purl/1416720.
@article{osti_1416720,
title = {Visualizing chemical functionality in plant cell walls},
author = {Zeng, Yining and Himmel, Michael E. and Ding, Shi-You},
abstractNote = {Understanding plant cell wall cross-linking chemistry and polymeric architecture is key to the efficient utilization of biomass in all prospects from rational genetic modification to downstream chemical and biological conversion to produce fuels and value chemicals. In fact, the bulk properties of cell wall recalcitrance are collectively determined by its chemical features over a wide range of length scales from tissue, cellular to polymeric architectures. Microscopic visualization of cell walls from the nanometer to the micrometer scale offers an in situ approach to study their chemical functionality considering its spatial and chemical complexity, particularly the capabilities of characterizing biomass non-destructively and in real-time during conversion processes. Microscopic characterization has revealed heterogeneity in the distribution of chemical features, which would otherwise be hidden in bulk analysis. Key microscopic features include cell wall type, wall layering, and wall composition - especially cellulose and lignin distributions. Microscopic tools, such as atomic force microscopy, stimulated Raman scattering microscopy, and fluorescence microscopy, have been applied to investigations of cell wall structure and chemistry from the native wall to wall treated by thermal chemical pretreatment and enzymatic hydrolysis. While advancing our current understanding of plant cell wall recalcitrance and deconstruction, microscopic tools with improved spatial resolution will steadily enhance our fundamental understanding of cell wall function.},
doi = {10.1186/s13068-017-0953-3},
journal = {Biotechnology for Biofuels},
number = 1,
volume = 10,
place = {United States},
year = 2017,
month =
}

Journal Article:
Free Publicly Available Full Text
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  • Plant cell walls are composed primarily of cellulose, hemicelluloses, lignins, and pectins. Of these components, lignins exhibit unique chemistry and physiological functions. Although lignins can be used as a product feedstock or as a fuel, lignins are also generally seen as a barrier to efficient enzymatic breakdown of biomass to sugars. Indeed, many pretreatment strategies focus on removing a significant fraction of lignin from biomass to better enable saccharification. In order to better understand the fate of biomass lignins that remain with the solids following dilute acid pretreatment, we undertook a structural investigation to track lignins on and in biomassmore » cell walls. SEM and TEM imaging revealed a range of droplet morphologies that appear on and within cell walls of pretreated biomass; as well as the specific ultrastructural regions that accumulate the droplets. These droplets were shown to contain lignin by FTIR, NMR, antibody labeling, and cytochemical staining. We provide evidence supporting the idea that thermochemical pretreatments reaching temperatures above the range for lignin phase transition cause lignins to coalesce into larger molten bodies that migrate within and out of the cell wall, and can redeposit on the surface of plant cell walls. This decompartmentalization and relocalization of lignins is likely to be at least as important as lignin removal in the quest to improve the digestibility of biomass for sugars and fuels production.« less
  • The isolation, purification, and partial characterization of a glucuronoarabinoxylan, a previously unobserved component of the primary cell walls of dicotyledonous plants, are described. The glucuronoarabinoxylan constitutes approximately 5% of the primary walls of suspension-cultured sycamore cells. This glucuronoarabinoxylan possesses many of the structural characteristics of analogous polysaccharides that have been isolated from the primary and secondary cell walls of monocots as well as from the secondary cell walls of dicots. The glucuronoarabinoxylan of primary dicot cell walls has a linear ..beta..-1,4-linked D-xylopyranosyl backbone with both neutral and acidic sidechains attached at intervals along its length. The acidic sidechains are terminatedmore » with glucuronosyl or 4-O-methyl glucuronosyl residues, whereas the neutral sidechains are composed of arabinosyl and/or xylosyl residues.« less
  • Wild type Bacillus subtilis, when grown on a soybean arabinan-galactan, secretes a ..beta..-1,4-galactanase which has been purified more than 200-fold from the culture fluid. Affinity chromatography was the most effective step in a purification procedure which resulted in a preparation that contained only a single 40,000 molecular weight protein band upon sodium dodecyl sulfate-disc gel electrophoresis. The purified galactanase digests a ..beta..-1,4-galactan purified from citrus pectin and digests partially the isolated cell walls of suspension-cultured sycamore cells. The predominant product of the enzymic degradation of the substrates tested is a 4-linked tetragalactose. Evidence is presented to support the hypothesis thatmore » the galactanase attacks its substrates in both an exo- and endo-manner. The products obtained upon galactanase digestion of the soybean arabinan-galactan demonstrate that the earlier proposal concerning the structure of this polysaccharide must be incorrect.« less