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Sweetening the Biofuels Production Process

Spathaspora passalidarum, one of the fungi sequenced for this paper (Courtesy of Thomas Kuster at USDA, Forest Products Lab)

Spathaspora passalidarum, one of the fungi sequenced for this paper
(Courtesy of Thomas Kuster at USDA, Forest Products Lab)

Currently, converting cellulosic biomass into biofuels is inefficient and costly.  One of the barriers to reducing costs and yields is that xylose, a five-carbon sugar that represents nearly half of available sugars in plant (in the form of hemicellulose), is extremely difficult and time-consuming to break down using enzymes sourced from conventional yeast strains.

In a paper published online Monday, July 25, in the Proceedings of the National Academy of Sciences (PNAS), a team of scientists including a group from the DOE JGI and the Great Lakes Bioenergy Research Center (GLBRC) have discovered a novel set of genes that enable yeast to more efficiently metabolize xylose to biofuel.
These scientists sequenced the genomes of types of fungi that survive on bark containing a lot of xylose, and have enough nutrients not just for their own growth but to feed the beetles living in the surrounding area.  The information allowed the scientists to identify the differences between non-xylose fermenting  yeasts and xylose fermenting yeasts.

“This research has provided us with a great genomic toolset,” says study’s lead author Dana Wohlbach, a postdoctoral researcher at UW-Madison. “We’re excited to explore new ways to increase yeast’s ability to consume xylose and improve ethanol production for cellulosic biofuels.”