Adaptive Evolution of Industrial Brewer’s Yeast Strains towards a Snowflake Phenotype

• Main Authors: Yeseren Kayacan, Thijs Van Mieghem, Filip Delvaux, Freddy R. Delvaux, Ronnie Willaert
• Format: Article
• Language: English
• Published: MDPI AG 2020-02-01
• Series: Fermentation
• Subjects: saccharomyces cerevisiae; industrial brewer’s strains; adaptive laboratory evolution (ale); snowflake phenotype; beer fermentation
• Online Access: https://www.mdpi.com/2311-5637/6/1/20

Flocculation or cell aggregation is a well-appreciated characteristic of industrial brewer&#8217;s strains, since it allows removal of the cells from the beer in a cost-efficient and environmentally-friendly manner. However, many industrial strains are non-flocculent and genetic interference to increase the flocculation characteristics are not appreciated by the consumers. We applied adaptive laboratory evolution (ALE) to three non-flocculent, industrial <i>Saccharomyces cerevisiae</i> brewer&#8217;s strains using small continuous bioreactors (ministats) to obtain an aggregative phenotype, i.e., the &#8220;snowflake&#8221; phenotype. These aggregates could increase yeast sedimentation considerably. We evaluated the performance of these evolved strains and their produced flavor during lab scale beer fermentations. The small aggregates did not result in a premature sedimentation during the fermentation and did not result in major flavor changes of the produced beer. These results show that ALE could be used to increase the sedimentation behavior of non-flocculent brewer&#8217;s strains.