Justin Jin for Nature
Geneticists have traced the history of beer’s most important ingredient: yeast. By sequencing the genomes of nearly 200 modern strains of brewer’s yeast, the research reveals how, over hundreds of years, humans transformed the wild fungus Saccharomyces cerevisiae into a variety of strains tuned for particular tipples.
Yeast gives beer its booze and bubbles by fermenting sugar into alcohol and carbon dioxide, but it also makes hundreds of chemicals that impart flavours such as bananas and cloves to a drink. Brewing yeasts differ in their production of these metabolites and in other traits such as their tolerance to alcohol.
To understand the basis for these differences, a team led by geneticist Kevin Verstrepen at the University of Leuven and the Flanders Institute of Biotechnology in Belgium, sequenced the genomes of 157 S. cerevisiae strains used to make ale and other fermented products, including wine, saké and bread . Their work is detailed in an 8 September Cell paper1.
An evolutionary tree of the yeast strains revealed distinct families of yeast used for making wine, bread and saké, and two distantly related groups of ale yeast, including strains from Belgium, Germany, Britain and the United States.
“This is a genomic encyclopaedia of ale yeasts that will serve researchers for years to come,” says Chris Hittinger, an evolutionary geneticist at the University of Wisconsin–Madison. Verstrepen’s team, meanwhile, is using genomics to churn out new strains of beer yeast.
Beer is one of civilization’s oldest intoxicants. A 5,000-year-old Sumerian tablet depicts an ancient keg party, while similarly aged pots from western Iran and northern China hold residues of beer ingredients, including barley and fermentation by-products. Given that …