Microsatellite PCR profiling of Saccharomyces cerevisiae strains during wine fermentation

Aims: Use of microsatellite PCR to monitor populations of Saccharomyces cerevisiae strains during fermentation of grape juice. Method and Results: Six commercial wine strains of S. cerevisiae were screened for polymorphism at the SC8132X locus using a modified rapid PCR identification technique. The strains formed four distinct polymorphic groups that could be readily distinguished from one another. Fermentations inoculated with mixtures of three strains polymorphic at the SC8132X locus were monitored until sugar utilization was complete, and all exhibited a changing population structure throughout the fermentation. Conclusions: Rapid population quantification demonstrated that wine fermentations are dynamic and do not necessarily reflect the initial yeast population structure. One or more yeast strains were found to dominate at different stages of the fermentation. Significance and Impact of the Study: The population structure of S. cerevisiae during mixed culture wine fermentation is dynamic and could modify the chemical composition and flavour profile of wine.