FLICKR, QUINN DOMBROWSKIFor thousands of years, humans have harnessed the natural metabolic activity of yeast, a microorganism that breaks down sugars into alcohol, to make beer and wine. Our taste for fermented drinks led to the domestication of certain strains of yeast, and a paper published last week (September 8) in Cell lays out some of this evolutionary history.
A team of scientists from University of Leuven, Vlaams Instituut voor Biotechnologie (VIB), and Ghent University in Belgium sequenced the genomes of 157 strains of Saccharomyces cerevisiae yeasts that are used to make beer, wine, bread, and other products on commercial scales. The team found five sublineages, with distinct phenotypes from wild yeasts, that have been cultivated for human use.
The researchers also dated the earliest cultivated yeast strains to the 1500s, which is likely a consequence of beer production in Europe moving from pubs into monasteries, where brewers began to retain yeast from one batch of beer to the next, reported Scientific American. As these early brewers fine-tuned their recipes, they also selected for favorable yeast strains. Domesticated yeasts have a greater capacity to metabolize sugar, fewer distasteful byproducts, and weaker reproductive abilities, compared to their wild-type cousins.
“Interestingly, although wine yeasts share their origins with beer yeasts, they show fewer signs of domestication. This is probably because wine yeasts are only used to ferment grape juice once a year, and survive in and around the winery for the rest of the year, where they may interbreed with feral yeasts,” Brigida Gallone and Jan Steensels of the University of Leuven told Scientific American. “In that sense, beer yeasts are like dogs, completely ‘tamed’ and adapted to their relation with humans, whereas wine yeasts resemble the wilder character of cats.”
“The flavor of the beer we drink largely depends on yeast," Kevin Verstrepen of the University of Leuven and VIB explained to Phys.org. “We're drinking the best beers now because ancient brewers were smart enough to start breeding yeast before they knew what they were doing. It was really an art.”