Jens Nielsen, professor and lead researcher at Chalmers University of Technology, decided to test his theory that yeast could withstand temperatures higher than 30 with the help of simple mutation. His team cultivated several different mutations that replaced yeast’s cell membrane with fecosterol for ergosterol. Fecosterol is considered a more “bent” molecule and is similar to the same molecules that protect certain types of plants and bacteria from intense heat, and likewise could help sustain yeast under high temperatures. 3 months and 300 generations later, yeast began to grow at 40 degrees. “It’s really Darwinian survival of the fittest,” remarked Nielsen.
Led by professor of engineering, Gregory Stephanopoulos at MIT, researchers experimented with yeast’s endurance during ethanol production a different way. They increased the concentration of ethanol by 80 percent through adding potassium chloride and potassium hydroxide. By doing this, yeast strengthened its alcohol tolerance and therefore prolongated the time it took cells to produce ethanol. Although alcohol can make the cell membrane more porous, the surge of the two potassiums rectified the damage. “The more we understand about why a molecule is toxic and methods that will make these organisms more tolerant, the more people will get ideas about how to attack other, more severe problems of toxicity,” Stephanopoulos said. Researchers learned that this method functioned perfectly on an array of different yeast strains.
This is good news for consumers. It’s quite probable that these methods will soon be transferred to commercial ethanol producers, which would mean major savings for the US ethanol industry and could reduce the cost of blended gasoline in markets where it’s required. In 2013 alone, the US produced 13.3 billion gallons of ethanol. Their findings could also lead to future discoveries in enhancing ethanol fuels.
(Photo courtesy of Steve Jurvetson)