From Discover Magazine By Veronique Greenwood
Yeasts are handy little critters: they help produce the alcohol that make wine and beer so deliciously intoxicating. But how they manage to show up on grapes in vineyards year after year, despite freezing winters when there is little for them to eat, is a bit of a mystery. Scientists thought birds could be keeping the yeasts in their guts through the winter, then sprinkling them (ahem) through vineyards in the spring, but turned out the microorganisms couldn’t survive that long in birds.
Now, scientists have identified a much more promising Florida timeshare of a gut: that of the social wasp. Social wasps feed on vineyard grapes, and their queens do survive the winter, emerging from hibernation to found new colonies in the spring. Italian researchers checked the gut microbes of 61 social wasps collected in Tuscany and other wine regions and found that there were scads of yeasts there, 393 strains to be exact. The wasps carried some yeasts that are similar to those found in the area’s wines, suggesting that they may indeed be a significant year-round reservoir of the microorganisms.
Italian wine owes some of its character to local yeasts, scientists have reported before, and this study lends credence to the idea that it’s not possible to separate conservation of local ecosystems and artisanal food production.
While this is certainly an intriguing idea, Saccharomyces cerevisiae can be pretty hardy little buggers on their own without needed to take shelter in the guts of insects. When presented with less than optimal growth conditions yeasts can revert into a semi quiescent survival mode where they build up stores of glycogen and trehalose to strengthen their membranes. Or given really unfavorable conditions yeasts can sporulate and create spores that can easily tolerate a wide range of environmental stresses.