Red-hued yeasts hold clues to producing better biofuels

In Wisconsin, a team based at the University of Wisconsin–Madison and the Great Lakes Bioenergy Research Center found clues in red-hued yeasts that could help harness the synthesis pathway for large-scale production of isobutanol as a biofuel. A red pigment called pulcherrimin, naturally produced by several strains of wild yeasts, is synthesized in part through the same biochemical pathway that researchers hope to use to improve production of isobutanol.

“Compared to first-generation biofuels, such as ethanol, isobutanol has a higher energy content, blends better with gasoline, causes less corrosion, and is more compatible with existing engine technology,” says GLBRC researcher Chris Todd Hittinger, a UW–Madison genetics professor who led the research. “Nonetheless, considerable barriers remain to producing this fuel sustainably from dedicated energy crops.”

The researchers used comparative genomics spanning 90 yeast species to identify the genes involved in pulcherrimin production. They found a cluster of four genes, which they named PUL1-4, that seem to play complementary roles. Through extensive genetic characterization, they determined that PUL1 and PUL2 are required to make the molecule, while PUL3 and PUL4 appear to help the yeast transport it and regulate its production.