It turns out that your wine may be less diverse than you thought. Scientists discovered that strains of wine yeast genomes actually lack diversity.
"It takes a tough yeast to ferment wine," said Anthony Borneman, one of the researchers involved in the new study. "Wine yeast need to be far more stress tolerant than strains used in brewing or baking, for example, to cope with the very high sugar and acidity levels of grape juice. Our results show that only a limited branch of the yeast evolutionary tree is currently used in winemaking."
Yeast actually helps contribute to the diverse flavors found in wine. It may also provide a component of a wine's "terroir," which is effectively the local set of conditions that give a wine its unique flavor. Traditionally, wine is fermented with the use of naturally occurring yeast. However, this can result in inconsistencies from vintage to vintage. That's why now most winemakers use pure active dried yeast starter strains that have been produced by commercial suppliers. This results in a more standardized wine that remains similar from year to year.
Currently, researchers are developing new strains of yeast that contribute to different flavor profiles in wine. But in order to create these strains, it's important to understand the genetic diversity of the yeast in the first place. That's why the scientists sequenced 212 strains of the yeast Saccharomyces cerevisiae.
So what did they find? It turns out that virtually all wine yeasts are closely related. Not only that, but they only carry a tiny fraction of the overall pool of S. cerevisiae genetic diversity. It's likely that the yeasts arose from a single ancestor, or from an inbred ancestral population.
With that said, subtle genetic distinctions could be seen between strains. This could be what is responsible for the unique flavors in wine. With that said, the findings show that there is limited scope for creating new strains solely from wine yeasts.
"We hope better understanding of yeast will allow us to tailor these organisms for specific uses, much as we have bred better varieties of domesticated plants and animals over millennia," Borneman of the Australian Wine Research Institute said.
The findings were published in April's issue of the journal G3 Genes Genomes Genetics.
