This project seeks an understanding of wild yeast fermentation and its relationship with terroir. It aims to determine species level regional differences between microbial populations from vineyards and uninoculated fermentations to determine if specific strains of yeast and bacteria reside in particular geographic or climatic zones.
Regional wine style expression, particularly where spontaneous fermentations are performed, may be due to differences in wine microbiota derived from the vineyard. Recent advances in metagenomics (genomic sequencing of mixed microbial communities) can provide detailed identification of the species, their proportions, and the complex microbial mixtures in a fast and cost effective manner.
The project will use next-generation sequencing and genomic methods to evaluate the contributions of various species of fungi, yeasts and bacteria in vineyard-to-wine time course experiments from samples sourced from multiple wine regions, to highlight the temporal and geographic dynamics of the microbial populations.
Given the importance of Saccharomyces cerevisiae, single cell genomic techniques will be developed to sequence a large cohort of S.cerevisiae strains isolated from both early and late stage fermentation. This will map the genetic diversity of S. cerevisiae that contribute to Australian wine fermentation and how this compares to strains from overseas and whether ‘wild’ Australian strains are supplanted by ‘commercial’ counterparts in the winery.
Once these regional differences are identified, key microbes will be isolated in pure culture to assess their contributions to the unique terroir or wine style(s) of the region.
Isolated strains will provide a key resource for wineries to enhance the expression of regional terroir through inoculation of existing microbes either in the vineyard or within individual ferments.