Ancient lager yeast discovered in Ireland

The ancestor of the original yeast that used in the very first lagers has been found in Europe for the first time.

Lager brewing, which first emerged in the 13th century in Bavaria, uses a species of yeast named Saccharomyces pastorianus, but it is the hybrid of two parents, Saccharomyces cerevisiae and Saccharomyces eubayanus.

While records show the first use of S. pastorianus was in breweries in southern Germany, the Saccharomyces eubayanus parent was never found in Europe only in South and North America, China, Tibet and New Zealand.

However, now, according to reports, researchers at University College Dublin have discovered and isolated Saccharomyces eubayanus in a wooded area of their campus.

The discovery, which took place during part of undergraduate research project to identify wild yeasts and sequence their genomes, was made when samples come from soil on two sites on the university campus, about 17 metres apart were collected.

As part of the study, the genome sequences of the two isolates showed that they are related to the ancestral Saccharomyces eubayanus strain that initially mated with Saccharomyces cerevisiae to form Saccharomyces pastorianus.

According to the researchers, this discovery of Saccharomyces eubayanus in Ireland offers firm proof that the yeast is native to Europe and has possibly lived in other parts of the continent, also supporting the theory that there were natural populations of the yeast in southern Germany in the Middle Ages that initially provided the parents of the first lager yeast.

University College Dublin’s professor and lead author on the project, Geraldine Butler, said: “This discovery is a fantastic example of research-led teaching. Our undergraduates have found more than a hundred yeast species in Irish soil samples over the past five years, and we’re delighted to stumble across Saccharomyces eubayanus on our own doorstep.”

Butler added: “We’re hoping to find a commercial partner to brew with it so we can find out what it tastes like.”

The research and findings can be found via the published works with Oxford Academic’s FEMS Yeast Research.