title: Sulfur dioxide addition at crush alters Saccharomyces cerevisiae strain composition in spontaneous fermentations at two Canadian wineries.
abstract: During winemaking, sulfur dioxide (SO2) is often added prior to the onset of alcoholic fermentation to prevent the growth of spoilage microorganisms and to create an environment that promotes the rapid colonization of the grape must by Saccharomyces cerevisiae. Most recent research has focused on the impacts of SO2additions on spoilage microorganisms or on the yeast community at a species level, but less is known about the impacts that SO2additions have on S. cerevisiae populations. We investigated whether different levels of SO2addition at crush (0, 20, or 40mg/L SO2) have an effect upon the relative abundance and composition of S. cerevisiae strains conducting spontaneous fermentations of two grape varietals at two commercial wineries. Yeast isolates collected from fermentations were identified to the strain level using microsatellite analysis. Commercial strains made up the majority (64-98%) of the S. cerevisiae strains isolated during fermentation, and most of these commercial strains were used as inoculants by their respective wineries. Different SO2additions were found to significantly alter S. cerevisiae strain compositions at both wineries (p≤0.002). The results of this study demonstrate that initial SO2addition significantly alters the S. cerevisiae strain composition in spontaneous fermentations, and highlights the dominance of commercial strains in commercial winery environments. Because different yeast strains are known to produce different chemical and sensory profiles, our findings have important implications for winemakers. In addition, adding different concentrations of SO2may be a way for winemakers to manage or control the strain composition during spontaneous fermentations.
authors.affiliation: Irving K. Barber School of Arts and Sciences, Unit 2 (Biology), University of British Columbia, 1177 Research Rd, Kelowna V1V 1V7, Canada. Electronic address: sydney.morgan@ubc.ca.
authors.forename: Sydney C
authors.initials: SC
authors.lastname: Morgan
authors.affiliation: Irving K. Barber School of Arts and Sciences, Unit 2 (Biology), University of British Columbia, 1177 Research Rd, Kelowna V1V 1V7, Canada.
authors.forename: Chrystal M
authors.initials: CM
authors.lastname: Scholl
authors.affiliation: Irving K. Barber School of Arts and Sciences, Unit 2 (Biology), University of British Columbia, 1177 Research Rd, Kelowna V1V 1V7, Canada.
authors.forename: Natasha L
authors.initials: NL
authors.lastname: Benson
authors.affiliation: Irving K. Barber School of Arts and Sciences, Unit 2 (Biology), University of British Columbia, 1177 Research Rd, Kelowna V1V 1V7, Canada.
authors.forename: Morgan L
authors.initials: ML
authors.lastname: Stone
authors.affiliation: Irving K. Barber School of Arts and Sciences, Unit 2 (Biology), University of British Columbia, 1177 Research Rd, Kelowna V1V 1V7, Canada.
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Durall
mesh_terms: D002170:Canada; D005285:Fermentation / Q000502:physiology*; D005421:Flavoring Agents / Q000032:analysis; D012441:Saccharomyces cerevisiae / Q000145:classification / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism*; D013458:Sulfur Dioxide / Q000494:pharmacology*; D027843:Vitis / Q000378:metabolism; D014920:Wine / Q000032:analysis / Q000382:microbiology*
chemical_list: D005421:Flavoring Agents; D013458:Sulfur Dioxide
keywords: Microsatellite strain typing; Population ecology; Saccharomyces cerevisiae; Spontaneous fermentation; Sulfur dioxide; Wine