Host: Jeff Fox with special guest, Stijn Mertens.

Mertens, a graduate student working with Kevin Verstrepen at the University of Leuven in Belgium, talks with Jeff Fox about their efforts to develop new yeast strains for making lager beers—imparting novel flavor and aroma notes without detracting from the freshness and drinkability of lagers.

Unlike other beers, lagers are brewed at low temperatures and with two special hybrid versions of yeast that date back about 600 years. Those hybrids aren’t so easy to produce, but Verstrepen and Mertens first made about 30 new varieties and, by now, about tenfold more, looking to find varieties that yield unusual flavors but still produce enough alcohol at cold temperatures to make lagers of acceptable uniformity and familiarity to brewers and to consumers. Underlying these practical challenges to make better beer are some important fundamental questions about what happens when two different species of yeast are forced to mate and produce stable hybrids. During that process, a good deal of genetic change takes place, but little is known about the details or what leads to genetic stability, according to Mertens. Part of his dissertation research entails investigating some of those processes at the molecular level.

This story was featured in the December 2015 issue of Microbe magazine

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