Elaine Cheng,* Jonathan Martiniuk*, Jonah Hamilton, Garrett McCarthy, and Vivien Measday
*University of British Columbia, Room 350, 2205 East Mall, V6T1Z4, Canada (elainecheng0803@yahoo.com.hk)

The yeast species Saccharomyces is present in vineyards and wineries and is responsible for the fermentation of grape must into wine. The potential contribution of Saccharomyces yeasts to regional characteristics of wine, or terroir, is gaining attention. Studies suggest that there are unique subpopulations of Saccharomyces strains in various winemaking regions, but Canadian vineyard-associated Saccharomyces populations have not been regionally profiled. This two-year study characterizes the Saccharomyces populations in Pinot noir vineyards of British Columbia’s Okanagan Valley (OKV), one of the major winemaking regions in Canada. Pinot noir grapes were collected in the 2016 and 2017 vintages from 13 vineyards across three OKV subregions spanning ~100 km (Oliver-Osoyoos, Penticton-Naramata, and Kelowna) and fermented in the lab to enrich for Saccharomyces yeasts. Among different subregions, there was a high disparity in spontaneous fermentation success rate over both vintages. In the 2016 and 2017 vintages, 1632 and 1440 Saccharomyces yeasts were isolated, respectively. To genetically characterize S. cerevisiae strains, microsatellite analysis was performed on all isolates by multiplex PCR of 11 genomic loci. Commercial S. cerevisiae strains were identified by comparing the microsatellite profiles to our commercial S. cerevisiae strain database of over 250 strains. Saccharomyces species and strain composition varied across subregions and vintages. In particular, S. cerevisiae was isolated in 2016, while S. cerevisiae and S. uvarum were isolated in 2017. Phylogenetic analysis suggests that potentially indigenous (non-commercial) sub-populations of S. cerevisiae are present in the OKV. Our long-term goal is to characterize the vineyard-associated Saccharomyces strains in the OKV and develop fermentation starter cultures that can produce wine with regional characteristics in a predictable and effective way.

Funding Support: British Columbia Wine Grape Council and Mitacs Accelerate