GLYCEROL PRODUCTION FROM SUGARS WITH PHOSPHOGLYCERATE MUTASE-DEFICIENT SACCHAROMYCES-CEREVISIAE PARTIALLY RESISTANT TO GLUCOSE REPRESSION

Mutants partially resistant to the repressive effect of glucose have been isolated from a Saccharomyces cerevisiae strain totally deficient in phosphoglycerate mutase activity (EC 5.4.2.1) by a selection procedure involving the catabolite-repressive effect of 5-thio-D-glucose (5TG). These mutants are able to resist glucose concentrations up to 15 g L-1 and exhibit several non-repressed metabolic pathways such as gluconeogenesis, glyoxylic shunt or mitochondrial respiratory chain. Moreover, when these mutants are grown in aerobiosis on ethanol and glucose as sole substrates, glucose is mainly converted into glycerol in order to maintain a normal redox balance. Optimal glucose and oxygen concentrations have been defined for resting cells in order to obtain a glycerol yield from glucose close to 100%. The physiological characteristics of one of these mutants led us to consider an application of this yeast strain in reducing the ethanol content of wines previously lowered in ethanol content by physical processes.