Galactan is a polymer of galactose, a six-carbon sugar that can be readily fermented by yeast into ethanol and is a target of interest for researchers in advanced biofuels produced from cellulosic biomass. Now an international collaboration led by scientists at the U.S. Department of Energy (DOE)'s Joint BioEnergy Institute (JBEI) has identified the first enzyme capable of substantially boosting the amount of galactan in plant cell walls.
Unlike ethanol, advanced biofuels synthesized from the sugars in plant cells walls could replace gasoline, diesel and jet fuels on a gallon-for-gallon basis and be dropped into today's engines and infrastructures with no modifications required. Also, adanced biofuels have the potential to be carbon-neutral, meaning they could be burned without adding excess carbon to the atmosphere. Among the key challenges to making advanced biofuels cost competitive is finding ways to maximize the amount of plant cell wall sugars that can be fermented into fuels.
"We have confirmed the identity of the GT92 enzyme as the first enzyme shown to increase the biosynthesis of galactan," says Henrik Scheller, vice president for JBEI's Feedstocks Division and director of its Cell Wall Biosynthesis group. "This identification of the first β-1,4-galactan synthase provides an important new tool for the engineering of advanced bioenergy fuel crops."
Scheller, who also holds an appointment with DOE's Lawrence Berkeley National Laboratory (Berkeley Lab), is the corresponding author of a paper in the journal Plant Cell that describes this work. The paper is titled "Pectin Biosynthesis: GALS1 in Arabidopsis thaliana is a β-1,4-Galactan β-1,4-galactosyltransferase." Co-authors were JBEI's April Liwanag, Berit Ebert, Yves Verhertbruggen, Emilie Rennie, Carsten Rautengarten, and Ai Oikawa, plus Mathias Andersen and Mads Clausen of the Technical University of Denmark.
Galactans are polysaccharid
|Contact: Lynn Yarris|
DOE/Lawrence Berkeley National Laboratory