From clear beers to the strongest and most fermented beer, beer owes much of its impressive variety to the hundreds of yeast strains that ferment it. Now, a team of geneticists has created the first family tree of these yeasts, using samples collected from almost a hundred breweries around the world.
Specifically, researchers from the Catholic University of Leuven (Belgium) analyzed the genes of 157 different varieties of yeast currently used to make beer -or wine, bread or sake-, they discovered that they all have a common ancestor that goes back to the year 1500.
“ The taste of the beer we drink largely depends on the yeast. We are drinking the best beers today, because the old brewers were smart enough to start breeding yeast before they even knew what they were doing. It was really an art, ”explains Kevin Verstrepen, co-author of the work.
Thus, the ancient brewers and bakers used a technique of “re-circulation”, where part of the dough was set aside to be mixed with the next batch of product. What they achieved with this was that they ended up domesticating the yeasts, that is, the human being modified the genetic composition of these microorganisms by selecting all those attributes that were most relevant.
By combining genetics and bioinformatics, scientists have traced back to the origin of that process. The conclusion is surprising: today’s beer, today’s industrial yeasts, come from five different strains of yeast with a particular use.
“ Four centuries of domestication have left their mark on yeast genomes. In various yeast lineages, various genes were amplified (increased in presence), deleted, or altered to optimize growth in beer fermenters or to improve flavor, “says study co-author Steven Maere.
Taking into account that the taste of beer depends a lot on yeast, it is not surprising that the genes related to an unpleasant taste present in yeasts of natural origin have disappeared over the centuries.
The beer family tree has been published in the journal Cell.
