Deploying a technique that promises to supercharge the development of biofuels, researchers at Princeton University have found a way to make yeast cultures glow when producing next generation fuels that could power cars and airplanes.

The glowing cultures address a major challenge that has slowed biofuel production: developing yeast strains that produce valuable chemicals and separating them from less productive strains of yeast. Before the development of this new technique, evaluating the performance of yeast was a slow, laborious process. Researchers had to grow separate yeast strains and independently evaluate each strain’s ability to produce fuel and other chemicals. This process could take days for each strain.

“The way we’d have to find better strains would be to take a few colonies, grow them overnight in cultures, and then start a fermentation process that would take between 24 and 48 hours,” said lead researcher José Avalos, assistant professor of chemical and biological engineering. “Now, we’re measuring hundreds of thousands of strains per minute. This is a several-orders-of-magnitude faster way to identify better strains.”

In a paper published Jan. 12 in Nature Communications, Avalos’s team described how they developed the biosensor for production of the biofuels isobutanol and isopentanol in yeast. Both are alcohols with a higher energy content than ethanol, which is the dominant biofuel now used in the United States. Like ethanol, isobutanol and isopentanol are produced by Brewer’s yeast (Saccharomyces cerevisiae), a single-celled fungus commonly used in making bread, beer and other alcoholic beverages. However, these advanced biofuels have much higher compatibility with existing gasoline infrastructure, allowing them to replace more fossil fuel, and can easily be upgraded to jet fuel.

“Scientists, engineers and regulators are still examining them, but these alcohols could be completely compatible with our current gasoline infrastructure,” said Avalos, the paper’s senior author. “Most cars couldn’t use gasoline with ethanol concentrations higher than 10 or 15 percent. However, they could use gasoline with much higher concentrations of isobutanol. So that means you could replace more gasoline with these advanced fuels.”

The current research began with the challenge of speeding up the development of yeast strains for isobutanol and isopentanol production. The rate at which scientists can introduce genetic diversity in yeast greatly outpaces the rate at which they can screen each strain to find those with increased biofuel production. Researchers thus had to figure out which genes to turn on or off and what enzymes or proteins were beneficial to the process using very slow, laborious and expensive methods.