10. A large set of newly created interspecific yeast hybrids increases aromatic diversity in lager beers

Stijn Mertens (1); (1) KU Leuven/VIB, Heverlee, Belgium

Technical Session 3: Yeast Biotechnology
Sunday, August 14  •  9:45–11:30 a.m.
Plaza Building, Concourse Level, Governor’s Square 15

Despite the enormous diversity in ale yeasts, the diversity of yeasts used in the lager beer industry (Saccharomyces pastorianus) is very limited. In fact, only two archetypes of lager yeasts are currently used in breweries, which are the result of one or two independent interspecies hybridization events, presumably originating from the 15th or 16th century, between the traditional brewer’s yeast Saccharomyces cerevisiae and Saccharomyces eubayanus. This confined genetic (and as a consequence phenotypic) diversity of lager yeasts is reflected in the relatively limited influence of the yeast strain on the aroma profile of lager beers. Because of the increased importance of product innovation to breweries, new lager yeasts with a diverse aroma production opens the window to re-enforce their position on the lager beer market. In this study, we generated a large set of new lager yeasts by crossing carefully selected S. cerevisiae and cold tolerant Saccharomyces species like S. eubayanus, S. kudriavzevii and S. mikatae. We obtained more than 250 new and unique lager strains. Next, these newly developed hybrids were genetically stabilized and screened for their fermentation capacity and aroma production in lager beer fermentations and their temperature tolerance. The applied approach resulted in a large set of new lager yeasts that display an enormous phenotypic diversity, with different lineages able to produce a whole new spectrum of lager beers with diverse aroma profiles. Moreover, these strains are directly applicable in industry, since the experimental procedure doesn’t rely on genetic modification.

Stijn Mertens received a B.S. degree in bioscience engineering from the University of Leuven, Belgium, in 2011 and an M.S. degree in bioscience engineering, major cell and gene technology, minor industrial microbiology, from the same university in 2013. He did his master thesis work in the VIB Laboratory for Systems Biology, led by Prof. Kevin Verstrepen, in 2012-2013, for which he was awarded the annual M.S. thesis prize of the Royal Society of Brewing Schools. He later joined the lab as a Ph.D. student.