| The complex interaction between yeasts and their environment is brought sharply into focus when wine fermentations fail to complete. Retrospective analyses of such failures are difficult or impossible because of the many combinations of factors that may lead to this undesirable outcome. These factors include choice of yeast strain, of which there are many, grape juice composition and winemaker intervention. The relationship between yeast strain genetics and wine yeast performance characteristics in response to grape juice compositional features is the focus of a number of projects at the Australian Wine Research Institute. Rather than focusing on small numbers of strains with specific characteristics we have taken a broader approach to understanding wine yeast diversity by assessing the genetic diversity of more than 200 commercial wine yeasts using whole genome sequencing and using that information to create a representative subset of 94 strains whose performance characteristics and contributions to stylistic attributes have been assessed. Taken together, this information provides a comprehensive evidence-based framework for understanding the behaviour and potential stylistic contributions of different wine yeast strains. As an example of the complexities underlying yeast strain fitness the genetic basis of copper and sulfite tolerance, and the physiological contradiction that this entails, will be discussed. An improved understanding of the advantages and limitations of different yeasts in concert with evolving methods for analysis of juice composition, means better informed yeast strain selection is definitely on the horizon. |
