Monday, April 19, 2010
LL Conference Facility (Hilton Clearwater Beach)
The economic production of biofuels from renewable biomass using Saccharomyces cerevisiae requires tolerance to high concentrations of sugars and alcohols. Here we applied an inverse metabolic engineering approach to improve alcohol tolerance in S. cerevisiae. Through transformation with a S. cerevisiae genomic library followed by serial cultivation and selection of transformants in the presence of high level of iso-butanol (1%), four independent S. cerevisiae transformants that showed improved iso-butanol and ethanol tolerance were identified. Overexpression of any one of INO1, DOG1, HAL1 and a truncated form of MSN2 resulted in remarkably increased ethanol tolerance. Especially, overexpression of INO1 elicited the highest ethanol yield and productivity under high concentrations of glucose or sugar mixtures containing galactose and glucose. The ethanol volumetric productivity and ethanol tolerance of the INO1-overexpressing strain increased by more than 70% and 340%, respectively, compared to the control strain. We expect these identified genes will serve as key components of a genetic toolbox for breeding yeast with high ethanol tolerance and efficient ethanol fermentation.