Over a billion dollars worth of ethanol is produced each year by using yeast. The ingredient is an important component in the production of ethanol, but certain conditions also limit yeast's capacity. Two separate studies, however, show that yeast can be manipulated to address these conditions.
Each study, one by researchers at Chalmers University of Technology and the other by scientists at the Massachusetts Institute of Technology (MIT), independently identified different means by which yeast tolerance could be boosted. Chalmers researchers found a way to make yeast heat-resistant, while MIT scientists produced yeast that could tolerate the toxicity of alcohol.
Heat is a problem for yeast because it can only thrive under certain temperatures. By mutating yeast through adaptive laboratory evolution, researchers at Chalmers were able to make it resistant to heat, allowing it to survive the production process and make ethanol.
Another problem with biofuel production is the fact that ethanol is toxic to yeast. Making yeast tolerant to alcoholic has been a long-term goal for metabolic engineers. MIT scientists first screened mutation combinations to find out if these could be used to increase alcohol tolerance but it wasn't until they altered the yeast's environment -- by adding potassium chloride and potassium hydroxides -- that they were able to produce the results they were looking for.
"The findings are a little bit unexpected, because we thought it was a complex problem. The solution turns out to be very simple," Huimin Zhao, a synthetic biologist and metabolic engineer at the University of Illinois, commented on the outcome.
Jens Nielsen, systems biology professor, headed the research team for Chalmers, while Gregory Stephanopoulos, a Willard Henry Dow Professor of Chemical Engineering, led the MIT team. Chalmers researchers were assisted by the Science for Life Laboratory, while MIT scientists collaborated with the Whitehead Institute for Biomedical Research.
Research conducted by Chalmers was funded by the Swedish Research Council, European Research Council and Novo Nordisk Foundation. MIT's work received funding from the Department of Energy and the university's Energy Initiative.
Both studies were published in the journal Science.