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For thousands of years, yeast have been utilized for food and beverage fermentations and more recently have become important model organisms for biomedical research. A catalog of phenotypic characteristics available to brewers can be attributed to domestication and artificial selection as well as chromosomal rearrangements and evolutionary events. Flocculation, the natural capacity for yeast cells aggregate into flocs at the end of the fermentation process, has a direct effect on the final fermentation product.. In order to flocculate, yeast strains must carry genes belonging to the flocculin protein family that will promote cell-cell adhesion. The flocculin genes, FLO1, FLO5, and FLO9, are highly homologous and all share a similar protein structure. The N-terminal domain is recognized as the sugar binding domain, allowing flocculin producing cells to selectively bind to mannose residues displayed on the cell wall of adjacent cells. In this study, the genetic variation in the N-terminal domain of flocculin genes FLO1, FLO5, and FLO9 was investigated. For each strain, the N-terminal domain was amplified by PCR and sequenced to assess the genetic variation between strains. Nonsynonymous variation in the flocculin proteins are predicted to correlate with variation in flocculation levels.


Faculty Advisor: Dr. Dale Beach

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