Are there regional microorganisms, and can they be harnessed to produce regionally distinct wine styles?
Regional wine style expression has been identified as one way that wine companies can differentiate their products in the market. An important aspect of terroir, particularly where spontaneous fermentations are performed, may be differences in wine microbiota. Focused microbiological research has shown that both vineyards and spontaneous fermentations contain diverse mixtures of microbial species (often with species being represented by multiple strains). However, the inability to efficiently and accurately assess the large numbers of samples required to understand such complex systems has limited subsequent insights.
Recent advances in metagenomics (genomic sequencing of mixed microbial communities), can address these issues by providing detailed identification of species, and their proportions, in complex microbial mixtures in a high throughput manner. In addition, through detailed genomic assembly of these datasets, the genetic make-up of individual strains within these mixtures can also be obtained to provide direct links between novel genetic and phenotypic characteristics. This type of metagenomic analysis has been refined for studies of wine fermentation at the AWRI and now provides the technical platform to answer important questions regarding Australian wine microbial terroir.
Metagenomic analysis is currently being performed on more than 100 samples (Chardonnay and Shiraz) sourced from thirty wineries across Australia during the 2016 vintage. This analysis will determine both the identity and proportions of yeast and bacteria that were present throughout the fermentation of these wines.
This represents the beginning of a highly detailed map of the microbial landscape of Australia’s wine-producing regions. Furthermore, by providing an understanding of the relationship between specific wild microorganisms and terroir, this could provide the means to exploit desirable winemaking attributes, while inextricably linking these wines to their place of origin.