The application of molecular techniques in wine microbiology

Many winemakers use pure Saccharomyces cerevisiae cultures, sometimes isolated from their own region, to produce wine of a more reproducible quality. As most of the industrial yeast strains belong to the S. cerevisiae group, anti cannot be distinguished and identified by classical microbiological methods, molecular techniques have recently been employed. Techniques such as mitochondrial DNA restriction analysis and chromosome electrophoretic analysis have been used to study the dynamics of both natural and inoculaled wine fermentations. Natural fermentation is a complex process during which it is possible to observe sequential substitutions of many different S. cerevisiae strains as the process proceeds. However, in inoculated fermentations, the inoculated strain prepared from active dried yeast clearly dominates. This microbiological simplification, together with advances in biotechnology, opens the way for the genetic modification of active dried yeast and thus the construction of strains that express metabolic activities that have consistent effects on the organoleptic characteristics of the resulting wines.