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. cer evisiae group, anti cannot be distinguished and identified by classica l microbiological methods, molecular techniques have recently been emp loyed. Techniques such as mitochondrial DNA restriction analysis and c hromosome electrophoretic analysis have been used to study the dynamic s of both natural and inoculaled wine fermentations. Natural fermentat ion is a complex process during which it is possible to observe sequen tial substitutions of many different S. cerevisiae strains as the proc ess proceeds. However, in inoculated fermentations, the inoculated str ain prepared from active dried yeast clearly dominates. This microbiol ogical simplification, together with advances in biotechnology, opens the way for the genetic modification of active dried yeast and thus th e construction of strains that express metabolic activities that have consistent effects on the organoleptic characteristics of the resultin g wines.