BioEnergy Research

, Volume 8, Issue 3, pp 1391–1400

Incorporation of Flavonoid Derivatives or Pentagalloyl Glucose into Lignin Enhances Cell Wall Saccharification Following Mild Alkaline or Acidic Pretreatments

  • John H. Grabber
  • Nicholas Santoro
  • Cliff E. Foster
  • Sasikumar Elumalai
  • John Ralph
  • Xuejun Pan
Article

DOI: 10.1007/s12155-015-9605-2

Cite this article as:
Grabber, J.H., Santoro, N., Foster, C.E. et al. Bioenerg. Res. (2015) 8: 1391. doi:10.1007/s12155-015-9605-2

Abstract

Partial substitution of normal monolignols with phenolic precursors from other metabolic pathways may improve the susceptibility of lignified biomass to chemical pretreatment and enzymatic saccharification for biofuel production. Flavonoids and gallate esters readily undergo oxidative coupling reactions, suggesting they could serve as alternate monomers for forming lignin in plants. To test this premise, primary cell walls of Zea mays (L.) were artificially lignified with normal monolignols plus various flavan-3-ol/phenolic ester derivatives, flavonol glycoside/gallate ester derivatives, or pentagalloyl glucose added as 0 or 45 % of the precursor mixture. Most alternate monomers readily copolymerized with normal monolignols, but wall-bound lignin was most efficiently formed with epicatechin, epicatechin gallate, epigallocatechin gallate, or hyperoside. Yields of glucose from a high-throughput digestibility platform were used to examine how lignin modifications affected the susceptibility of cell walls to enzymatic hydrolysis following alkaline or acidic pretreatments of different severities. With the exception of hyperoside, incorporation of alternate monomers into lignin improved yields of enzymatically released glucose by 18–60 % after mild alkaline pretreatment and by 6–34 % after mild acid pretreatment. Responses due to lignin modification diminished as pretreatment severity increased. Overall, our results suggest that apoplastic deposition of pentagalloyl glucose or gallated flavan-3-ols such as epicatechin gallate or epigallocatechin gallate for incorporation into lignin could be promising plant genetic engineering targets for improving sugar yields from grass biomass crops that are subjected to low-temperature alkaline pretreatments.

Keywords

Monolignols Genetic engineering Pretreatment Enzymatic hydrolysis Cellulosic biofuel 

Copyright information

© Springer Science+Business Media New York (outside the USA) 2015

Authors and Affiliations

  • John H. Grabber
    • 1
  • Nicholas Santoro
    • 2
  • Cliff E. Foster
    • 2
  • Sasikumar Elumalai
    • 3
  • John Ralph
    • 4
  • Xuejun Pan
    • 3
  1. 1.USDA-ARS, U.S. Dairy Forage Research CenterMadisonUSA
  2. 2.D.O.E. Great Lakes Bioenergy Research CenterMichigan State UniversityEast LansingUSA
  3. 3.Department of Biological Systems EngineeringUniversity of Wisconsin–MadisonMadisonUSA
  4. 4.Department of Biochemistry and D.O.E. Great Lakes Bioenergy Research Center, Wisconsin Energy InstituteUniversity of Wisconsin–MadisonMadisonUSA

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