Global Climate & Energy Project
Biomass EnergyEfficient Biomass Conversion: Delineating the Best Lignin Monomer-Substitutes
Start Date: December 2008
John Ralph, Xuejun Pan, and Sara Patterson, University of Wisconsin, Madison
To delineate a set of approaches for successfully altering lignin structure, in a way that allows plant cell wall breakdown to produce biofuels in more energy-efficient manner, by providing alternative plant-compatible monomers to the lignification process.
Over the past decade it has become apparent that the metabolic malleability of lignification, the process of polymerization of phenolic monomers to produce lignin polymers, provides enormous potential for engineering the resistant polymer to be more amenable to processing. Massive compositional changes can be realized by perturbing single genes in the monolignol pathway, particularly the hydroxylases. More strikingly, monomer substitution in the process of lignification, particularly in cases where a plant’s ability to biosynthesize the usual complement of monolignols is compromised, has been observed. These substitutions include products of incomplete monolignol biosynthesis such as 5-hydroxyconiferyl alcohol, ferulic acid, and coniferaldehyde and sinapaldehyde. This suggests that lignin composition can be altered leading to plants with characteristics for improved processing to biofuels.
ApproachTo delineate the best monolignol substitutes, promising plant-compatible precursors (monomers) will be synthesized and tested for their compatibility with lignification in biomimetic systems (Figure 1). Improvements in biomass processing from the incorporation of these new monolignols will be elucidated in biomimetic cell wall systems.