Improving ethanol tolerance of Saccharomyces cerevisiae by overexpressing an ATP-binding cassette efflux pump

We investigated expression of an efflux pump belonging to a class of membrane transporters that export toxic chemicals from cells to improve ethanol tolerance of Saccharomyces cerevisiae. A presumed multidrug/solvent efflux pump, ADP1 of S. cerevisiae BY4741, was cloned and overexpressed in the same strain. Overexpression of the gene allowed the engineered strain to show higher specific growth rate and greater ethanol productivity compared to its parental strain in the presence of 5-7.5% (v/v) ethanol. The ethanol productivity and the amount of ethanol produced were 20% to 50% higher than those of the wild-type strain. These results indicate that overexpression of ADP1 led to an increase in tolerance to ethanol-induced stress, which allowed the engineered strain to produce ethanol more efficiently in the presence of ethanol.