The conversion of the lignocellulosic biomass into ethanol fuel is an interesting alternative to the present bioethanol production industry based on food-related feedstocks. Fermentation of lignocellulosic hydrolysates however, is very challenging to yeast because besides fermentable sugars, inhibitory compounds derived from cellulose, hemicellulose and lignin degradation during pretreatment of the biomass are also found in the broth. Acetic acid is among these compounds and it can be released from hemicellulose to such an extent that yeast fermentation is completely compromised. Furthermore, the yeast most commonly used for this purpose, S. cerevisiae, is not able to ferment xylose, which could constitute up to 40% of the lignocellulosic material. In this project we target the development of robust xylose fermenting S. cerevisiae strains.
Our project aims at increasing the tolerance of yeast to acetic acid and other acids. Furthermore, the expression of key genes associated to higher robustness and the related effect on xylose fermentation is also studied.