Beer Yeasts Are Surprisingly Diverse, Study Finds
As old as it is, scientists and historians don’t entirely know how beer brewing evolved across the world. Now, a new study published in Current Biology finds that compared to other alcohols like wine, the genetics of beer yeasts are incredibly diverse, possibly highlighting how inventive early beer-makers were. Most strains of yeast used to brew beer come from a different genetic line than the yeasts used to make other alcohols, the study found.
Different yeasts yield different beer varieties. Ales are made with Saccharomyces cerevisiae (commonly known as baker's yeast), as are wine and bread, while lagers are fermented with S. pastorianus. The S. cerevisiae yeasts ferment at the top of the liquid, while the S. pastorianus ferment at the bottom.
The study found that genetically, beer yeasts are very different from each other. “Whereas wine yeasts from any place in the world, say France and New Zealand, cluster in the same group and are genetically very similar, quite the opposite is true for beer yeasts,” said a press statement by the study's lead author José Paulo Sampaio, who researches yeast ecology at Nova University of Lisbon. He and his colleagues looked at genetic data from more than two dozen yeast strains.
They found that top-fermenting beer yeasts like S. cerevisiae mostly belong to one clade (or group with a common ancestor) that’s split up into three subgroups: mostly German and Belgian beers; mostly British, Australian, and American ales; and a subgroup of other strains used for kölsch beers and a California ale. Of the 30 top-fermenting yeasts in the study, 23 belonged to this main beer clade, which showed genetic diversity that was more than twice that found in wine yeasts.
Meanwhile, some other beer yeast strains were closely linked to the yeasts used to make sake, wine, and bread. This indicates that the main genetic group of beer yeasts—the top-fermenting ones—was likely domesticated in a completely separate event than the strains related to wine and sake yeasts.
“Our results revealed that the most important wheat beer strains are in the sake clade and seem to have a completely different ancestry as compared with the other wheat beer yeasts,” Sampaio and his co-authors write. Those wheat beer strains include the type of yeast used in 90 percent of Bavarian wheat beer production, they note.
Some of the other strains used in beer-brewing were related to sake and wine yeasts. “The search for new beer types might have [led brewers to] co-opt wine, bread, and sake strains for beer brewing, as evidenced by our results,” they hypothesize.
Love beer history? Go enjoy a brew at one of the multiple European breweries that have been operating continuously for almost a thousand years.
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