Construction of a flocculating yeast for fructose production from inulin

Construction of flocculating yeast lacking for fructose utilisation was realised by integration of the FLO1 flocculation gene in the ribosomal DNA of an hexokinase deficient (hxk1, hxk2) Saccharomyces cerevisiae strain (ATCC36859). Simultaneous production of ethanol and fructose was obtained from glucose/fructose mixtures or from hydrolysed Jerusalem artichoke extracts using the transformed yeast in batch fermentations and in a continuous reactor with internal biomass recycle. This allowed the production of 5 g ethanol/L and 48 g sugars/L containing up to 99 % fructose from diluted hydrolysed Jerusalem artichoke extracts containing 60 g sugars/L.