After thousands of years of unwitting domestication, brewing yeasts — the microorganisms that ferment a brewer’s tepid slop of grain, water and hops into beer — are as diverse as the beer they make. And now two research teams, from White Labs and a Belgian genetics laboratory, are mapping outtheir sprawling genealogy, creating the first genetic family tree for brewing yeasts and the beers they make.
The laboratories have sequenced the DNA of more than 240 strains of brewing yeasts from around the world. Alongside samples from breweries like Sierra Nevada, Duvel Moortgat and Stone, “we’ve thrown in a few wine, bakers, bio-ethanol and sake yeasts to compare,” said Kevin Verstrepen, director of the lab in Belgium.
By getting a line-by-line reading of the 12 million molecules that make up the DNA of each yeast, Dr. Verstrepen said, the researchers will be able not only to tell how closely related two yeasts are (is Sam Adams’s closer to Stone’s, or Sierra Nevada’s?) but to answer other important questions: which breweries started with the same strains of yeasts, how these organisms evolved over time and, of course, how all of it translates to taste.
“Yeasts can make over 500 flavor and aroma compounds,” said Chris White, the founder of White Labs, affecting a beer’s alcohol level, clarity and texture. But while brewing yeast is one of the best-studied organisms in molecular and cell biology, exactly how its genes translate to brewing properties is still poorly understood.
By comparing the DNA of hundreds of yeasts, along with information on how they act and brew differently, “we’ll have a unique window into the genetic code,” said Mr. Prahl, who is leading the experiment at White Labs. He is comparing each yeast’s sequencing information with brewing data on more than 2,000 batches of beer — including the four he was tasting.