Yeast has been a part of our lifestyle for centuries now. From bread to beer, the importance, and the indispensability of yeast are undeniable. However, a lot remains unknown regarding its biodiversity, especially of the specimens which occur naturally. Researchers, therefore, have now set out on a quest to find more about the various species of yeasts, which are used in the production of lager–one of mankind’s finest inventions during the period of the Renaissance.
Chris Todd Hittinger, the Principal Investigator at the Hittinger Lab, has made the lager yeast the topic of his research. People, he notes, have experimented with yeast, combining and mixing it in different ways and means, absolutely unaware of their involvement in those processes. Yeasts which are used in brewing lager are a hybrid species. The hybrid comprises two diverse yeast species. The first species is Saccharomyces cerevisiae. It prefers the Mediterranean room temperature. It has been functional in the production of wines, ales, and even bread for centuries.
The other species, Saccharomyces eubayanus, prefers a colder environment and is a rather recent discovery. Although the discovery of the S. eubayanus strain was a recent event, it’s existence can be traced back to the 15th century. In fact, upon its discovery, notes Hittinger, it was revealed that the S. eubayanus variety was the very same species which hybridized with the S. cerevisiae species to create the hybrid species which was used to create lager.
Like so many great discoveries and inventions, the discovery of the lager was also an accident. The Bavarians, around the 1400s, accidentally discovered that the beers which were kept inside the caves throughout the winter season had continued their fermentation process. More importantly, as a result of this continuation, the brew had become lighter and even smoother. Soon, this particular brew started to take over the taste buds of the masses, and it hasn’t stopped ever since.
The lager yeasts have two distinct lineages favored by the brewers–the Frohberg lineage and the Saaz lineage. The origin of these hybrid strains is shrouded in mystery. This is where charting the family tree of the lager yeast becomes important. In fact, Hittinger’s research has been trying to resolve this controversy regarding its single versus multiple origins.
The idea was to use the genome sequence generated by the two hybrids and to ascertain the changes that have occurred in them. A further comparison between these hybrids and their naturally occurring specimens led to the completion of the genome sequence of both the species.
The researchers had anticipated a single hybridization event before the divergence of the two lineages. However, in an unexpected turn of events, it was revealed that the genome of S. cerevisiae had mutated almost 10 times more than that of S. eubayanus. Therefore, the S. cerevisiae genome had diverged long before it hybridized with S. eubayanus.
To conclude, the lager yeast can be, therefore, said to have two distinct origins. Two different hybridization events with two different varieties of the S. cerevisiae with a similar S. eubayanus strain has led to the creation of the Frohberg and Saaz lineages.
According to Hittinger, investigation regarding the different lineages of yeast has opened up newer avenues. More research could lead to the creation of designer strains using wild species and domesticated ones. Hittinger is taking inspiration from the innovative approaches of the biofuel industry. He believes that the possibility of innovation is endless, and one can only imagine the number of new flavors and types of beers heading our way. Yeasts FTW!