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Flocculation gene variability in industrial brewer's yeast strains
Sebastiaan E Van Mulders1, Maarten Ghequire, Luk Daenen
1Centre for Malting and Brewing Science, Department of Microbial and Molecular Systems, Faculty of Bioscience Engineering, Katholieke Universiteit Leuven, Kasteelpark Arenberg 22, 3001 Leuven, Heverlee, Belgium. Sebastiaan.vanmulders@biw.kuleuven.be
Applied Microbiology and Biotechnology
|September 3, 2010
Summary
Brewer's yeast flocculation, crucial for brewing, is controlled by FLO genes. Genetic variation in these genes, particularly FLO1 and FLO9, complicates controlling yeast separation from beer.
Area of Science:
- * Microbiology
- * Yeast Genetics
- * Brewing Science
Background:
- * The brewer's yeast genome contains the 'Flo' flocculin family, essential for flocculation.
- * Controlled flocculation is vital in the brewing industry for cost-effective and eco-friendly yeast separation.
- * FLO genes exhibit rapid evolution and divergence, impacting flocculin structure and flocculation characteristics unpredictably.
Purpose of the Study:
- * To investigate the genetic basis of flocculation in industrial brewer's yeast strains.
- * To screen for characteristic FLO gene sequences in ale and lager yeast strains with varying flocculation strengths.
- * To understand how genetic variability in FLO genes affects flocculation behavior.
Main Methods:
- * Selection and screening of 18 yeast strains (16 industrial, 1 lab, 1 reference) with diverse flocculation abilities.
- * Analysis of characteristic FLO gene sequences (FLO1, FLO9, FLO10) within the selected strains.
- * Identification of specific FLO gene markers and alleles, including Lg-FLO1.
Main Results:
- * Distinct FLO gene marker patterns were observed across most yeast strains.
- * FLO1 and FLO10 markers were found in only five strains, while FLO9 was ubiquitous.
- * Three strongly flocculating ale yeast strains unexpectedly possessed a 'lager' yeast FLO gene marker, specifically a complete Lg-FLO1 allele.
Conclusions:
- * Significant genetic variation exists within flocculation genes (FLO) in industrial brewer's yeasts.
- * The presence of a 'lager' FLO1 allele in ale yeasts highlights complex gene flow and evolutionary dynamics.
- * This genetic diversity poses challenges for understanding and controlling yeast flocculation in brewing.
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