Genetic engineering of a yeast strain fermenting both pentose sugars, L-arabinose and D-xylose.
Beate Wiedemann, Eckhard Boles
Institut fuer Mikrobiologie, J. W. Goethe-Universitaet, Marie-Curie-Str. 9, Frankfurt / Main, 60439, Germany
Bioethanol produced from plant biomass is a promising alternative to fossil transportation fuels. In industrial processes the yeast Saccharomyces cerevisiae is commonly used for ethanol production. However, to make good economic sense it is necessary to obtain a strain with an expanded substrate range and high ethanol yields. Although S. cerevisiae is able to produce high ethanol yields from hexoses, it lacks the ability to ferment pentose sugars. Therefore, the development of a yeast strain capable to ferment pentose sugars would be of great industrial interest. We have constructed an S. cerevisiae strain able to utilise both pentoses, L-arabinose and D-xylose, which are the most widespread pentose sugars in our biosphere. For this, we integrated a plasmid expressing a D-xylose-utilising pathway into the genome of a yeast strain already engineered for L-arabinose fermentation. Co-fermentation of D-xylose and L-arabinose was tested by physiological analysis. We will present the first recombinant S. cerevisiae strain able to ferment both pentose sugars L-arabinose and D-xylose into ethanol.