|WANG, XUEFEI - Washington State University|
|SCHLATTER, DANIEL - US Department Of Agriculture (USDA)|
|GLAWE, DEAN - Washington State University|
|EDWARDS, CHARLES - Washington State University|
|ABATZOGLOU, JOHN - University Of Idaho|
Submitted to: International Journal of Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/30/2021
Publication Date: 5/6/2021
Citation: Wang, X., Schlatter, D.C., Glawe, D.A., Edwards, C.G., Weller, D.M., Paulitz, T.C., Abatzoglou, J.T., Okubara, P.A. 2021. Native yeast and non-yeast fungal communities of Cabernet Sauvignon berries from two Washington State vineyards, and persistence in spontaneous fermentation. International Journal of Food Microbiology. S0168-1605(21)00184-7. https://doi.org/10.1016/j.ijfoodmicro.2021.109225.
Interpretive Summary: Production and consumption of wines made solely with native yeasts and bacteria have risen across Europe, USA and Washington State. Production of alcohol, flavors and aromas during native fermentation is driven by the microbial communities that live on grape berries and in wine production environments. However, lack of predictability of the microbial composition of native fermentations poses the risk of vintages with undesirable flavors or aromas. In this pilot project, we used advanced DNA sequencing technologies to identify which yeasts were present in two Cabernet Sauvignon vineyards, and how the yeasts persisted during small-scale native fermentations. The project complements ongoing studies at the Wine Science Center, Prosser, WA, opens doors to additional comparisons among Washington AVAs, vineyards and grape cultivars, and provides leads for sensory testing in larger-scale fermentations.
Technical Abstract: Background: Washington State, USA is known for its production of premium wines, yet not much is understood about the microbial composition of grape berries that might condition vineyard health and wine quality in Washington. To address this knowledge gap, next-generation sequencing was used to identify native yeast species on berries of cultivar ‘Cabernet Sauvignon’ from two Washington vineyards at veraison and harvest in 2015 and 2016. These species were followed in laboratory-scale native fermentations generated from the berries. Results: Both yeasts and non-yeast fungi were identified in berry and fermentation samples using sequences of the internal transcribed spacer region (ITS1) of the nuclear 26S ribosomal RNA gene. Vineyard location, year and berry developmental stage were the primary factors that accounted for the variation among yeast communities. One hundred and nineteen different yeast sequences representing 52 groups were identified to genus or species, 16 of which had not been reported on grapes in other studies. A common set of 22 yeast taxa, including species of Phaeococcomyces, Vishniacozyma and Metschnikowia, were observed at both locations and in both years, and the Metschnikowia persisted in fermentation samples. Conclusions: Cabernet Sauvignon grown in Washington State harbored many of the yeasts found on this cultivar in other parts of the world, with the exception of the prevalence of cold-tolerant species. The findings also underscored the significance of location and harvest year as major factors in native yeast community diversity.