Large-scale systems biology approach to select and create novel yeast strains with superior fermentation characteristics

Technical Session 22: Yeast IV Session
Kevin J Verstrepen, CMPG Laboratory for Genetics and Genomics, 3001 Leuven, Belgium

ABSTRACT: We present a resource that allows us to select and create superior brewing yeasts. Compared to certain other fermentation industries (bread, wine), the beer industry has spent relatively little attention on the selection and optimization of brewing yeasts. This is at least partly due to the fact that each brewery often uses one or a few particular, proprietary yeasts, whereas wine and bread yeasts are often produced by large, specialized companies. This implies that may breweries are using sub-optimal yeasts and that there is a vast potential for selection and breeding of superior beer yeasts. In the past years, our research team has gathered a large collection of more than 500 different industrial Saccharomyces yeasts. Each of these yeasts was screened for more than 100 different industrial properties, including such traits as fermentation capacity, ethanol resistance, temperature tolerance, flavor production, and flocculation. In addition, we have also assessed the genetic background of each of the yeast strains. Together, this large set of data (500 yeasts × 100 properties × genetic background) allows us to select yeasts with specific properties to accommodate specific beer types and fermentation properties. Moreover, using our database also allows us to select ideal parents to generate novel yeasts (through crossing, protoplast fusion, or directed evolution) with improved or combines properties. Last, but not least, advanced data analysis (including biclustering methods) allows us to find correlations between specific traits and/or genotypes.

Kevin Verstrepen studied biological engineering at the University of Leuven. For his M.S. thesis, Kevin joined Isak Pretorius’ group at Stellenbosch University to study flocculation in wine and beer yeasts. Kevin subsequently focused on yeast genes involved in flavor formation during fermentation. After obtaining his Ph.D., Kevin joined the lab of Gerald Fink at MIT. Revisiting the topic of his M.S. thesis, Kevin discovered that the genes responsible for yeast flocculation contain arrays of highly unstable repeats in their DNA sequence. After spending two years at MIT, Kevin joined Harvard University as a Bauer Fellow. In 2007, he was promoted to lecturer and started teaching industrial microbiology to undergraduate students. Meanwhile, Kevin headed a research team dedicated to studying fundamental genetics, using yeast cells as a model system. In 2009, Kevin moved his team to Leuven University, where he holds a dual appointment as associate professor and research director at the Flanders Institute for Biotechnology (VIB). His team continues to investigate eukaryotic genetics and epigenetics, with specific interest in industrial microbiology.