The dynamics of microbiomes in the winery

To conduct fermentation for winemaking either selected and commercially available yeast strains are inoculated or a spontaneous fermentation awaits the onset of fermentation without adding any yeast culture. Most scientific findings report for the latter approach a dominance of yeast strains originating from the cellar in contradiction to the common belief that vineyard derived microbiome is responsible for spontaneous fermentations. Recent application of modern genetic tools by Mills and coworkers at UC Davis however elucidated site specific microbiota on grapes from different vineyards and vintages. Furthermore, the microbial contribution of particular sources in wineries such as presses, tanks or barrels have been characterized.

It is the main objective of this PhD study to identify and profile in cooperation with David Mills (UC Davis) the different origins of the microbiome, mainly yeast, conducting spontaneous fermentation and to follow their succession during the winemaking process. Concurrently, the formation of aroma compounds of the yeasts are monitored in cooperation with Vicente Ferreira (Univ. Zaragoza) and finally the sensory properties of the finished wines will be evaluated by quantitative means. Mathematical modelling will be utilized to link the yeast data set with the production of aroma compounds and in parallel with the achieved sensory characteristics of the wines. This will enable us to gain a deeper understanding of the role of vineyards and wineries in sustaining beneficial microbial flora and thus determine measure to exploit such biodiversity in guided winemaking process.

Further information

• Viticulture and Oenology Department (VOD), DLR-Rheinpfalz
• University of California