Jonathan (Jay) Martiniuk, Jonah Hamilton, and Vivien Measday* 
*University of British Columbia, 2205 East Mall, Vancouver BC V6T 1Z4, Canada (vmeasday@mail.ubc.ca)

Wine is produced by one of two methods: inoculated fermentation, during which a commercially-produced, single Saccharomyces cerevisiae yeast strain is used, or spontaneous fermentation, where yeast present on grape and/or winery surfaces carry out fermentation. Spontaneous fermentation is characterized by a diverse succession of yeast species, ending with one or multiple strains of S. cerevisiae dominating the fermentation. The resulting wines may be more organoleptically complex due to the participation of a wide range of yeast species. Yeasts participating in spontaneous fermentation are derived either from the vineyard or the winery itself. In the vineyard, yeast population composition is highly heterogeneous, differing between regions and even between adjacent vineyards. While the vineyard fungal microbiome has been profiled in wine regions worldwide, this has not yet been explored in Canada. Using amplicon sequencing of the intergenic transcribed spacer region, we examined the impact of winery environment on yeast population structure in spontaneous fermentations over two vintages by comparing yeast populations in aseptically fermented grapes from a British Columbian Pinot noir vineyard to populations in winery-conducted fermentations of grapes from the same vineyard. We also characterized the vineyard-associated yeast populations in two additional, geographically separate Pinot noir vineyards (1km radius) farmed by the same winery to assess whether distance drives yeast population structure. To examine yeast population dynamics during fermentation, we profiled yeast populations in 100 samples from various stages of fermentation immediately after crushing and at early, mid and late fermentation. Pinot noir yeast species populations will be compared to previously-described S. cerevisiae strain populations from the same fermentations. This research is the first to characterize vineyard-associated yeast populations in Canada and is the first step in a regional yeast population study to identify species with novel oenological applications.

Funding Support: Natural Sciences and Engineering Research Council of Canada, Genome British Columbia, American Wine Society Educational Foundation, Stoneboat Vineyards, Okanagan Crush Pad