MONITORING OF YEAST POPULATION CHANGES DURING A CONTINUOUS WINE FERMENTATION BY MOLECULAR METHODS

Molecular methods were used to monitor the changes in the yeast population and the capability of Saccharomyces cerevisiae used as a starter culture to dominate a continuous wine fermentation. Plating analysis was performed to isolate yeasts present in the must, and molecular analysis was used to characterize the strains. Restriction fragment length polymorphism of the 18S rRNA gene and ITS1 region and mitochondrial DNA (mtDNA) restriction endonuclease analysis (REA) were exploited. Denaturing gradient gel electrophoresis of the 5' end 26S rRNA gene obtained from DNA extracted directly from must was used to profile the yeast population, avoiding the potential biases of traditional methods. The predominance of S.cerevisiae population throughout fermentation was observed. Identical patterns were obtained from all the S. cerevisiae strains isolated using mtDNA-REA analysis, demonstrating the capability of the starter culture to perform the continuous fermentation.