<p>The aim of this study was to detect the population dynamics of Saccharomyces cerevisiae wine yeast strains during inoculated and spontaneous fermentations in three wineries located in the Okanagan Valley of British Columbia, Canada. In total, 9 guided and 3 spontaneous fermentation tanks containing Vitis vinifera L. var. Pinot Noir berries were sampled from four distinct stages of fermentation (cold-soak, early, mid, and end). A total of 720 yeasts were isolated and identified from the 2010 Harvest year. S.cerevisiae strains were distinguished using PCR amplification of six hyperviariable trinucelotide microsatellite loci and identified upon comparing their genetic fingerprints to a published comparative microsatellite active dry yeast (ADY) database and an ADY database that was constructed for each winery. DNA sequence analysis of the internal transcribed spacer (ITS) and the D1/D2 domain regions of the large subunit of ribosomal DNA were used to identify non-S. cerivisiae spp. Twelve commercial S. cerevisiae strains and 20 unique S. cerevisiae fingerprints, or ‘unknown’ strains, were detected from all three wineries. The detection of ‘unknown’ S. cerevisiae isolates may be due to recombination events of commercial strains generating hybrid S. cerevisiae isolates or they may be of natural origin. Non-Saccharomyces species were the dominant yeasts in the cold-soak stage and S. cerevisiae strains were mainly isolated during early, mid, and end stages of fermentation. At two of the 3 wineries, the commercial S. cerevisiae starter cultures were not necessarily the dominant or finishing strain and a non-inoculant commercial strain, Lalvin ICV-D254, was consistently detected in both guided and spontaneous fermentations. The dominance of Lalvin ICV-D254 appeared to be correlated with whether the winery had used this strain in fermentations of other grape varietals. In only one of the three wineries did spontaneous fermentation have a substantial strain diversity increase as compared with the inoculated fermentations.</p>
<p><strong>Acknowledge of funding sources:</strong><br />
The authors are grateful for financial support received from Natural Sciences and Engineering Research Council (NSERC) and Quails’ Gate Estate Winery.<br />
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