Helene Ver Eecke (1), Alec Rippe (1); (1) Metropolitan State University of Denver, Denver, CO, U.S.A.

Yeast, Fermentation, and Microbiology

Yeast harvesting is often performed on large volumetric samples and/or samples with high viable cell numbers. On occasion preciously rare bottles of beer come into the hands of brewing microbiologists and chemists with perhaps only 12 oz to work with and potentially little to no viable cells. This research problem requires significant forethought on how to process the sample to maximize one’s likelihood of recovering and culturing any viable cells. Our research goal was to determine an optimal protocol for recovering and culturing yeast from a single bottle of beer. This protocol can be applied to various beer samples to confidently assess if the sample contains any viable cells and to successfully get those cells into pure culture. Various permutations of cell concentration methods (filtration/centrifugation), handling methods (anaerobic/aerobic/microaerophilic), and media types (general/selective and solid/liquid) were tested to determine the optimal protocol that yields the highest rate of cells in culture. These experimental protocol screenings were performed on spiked controls (a mixture of a known viable cell concentration and cell-free beer) and then unfiltered beer samples from various commercial bottles with unknown cell concentrations. Knowledge gained from these experiments yields a best approach to process a one-of-a-kind bottle sample. This precious, decades-old sample was provided by the historic Tivoli Brewery, which recently reopened in the Tivoli building in Denver, CO.

Helene Ver Eecke received a B.A. degree in biology from McDaniel College and a Ph.D degree in microbiology from UMass Amherst. She then worked as a senior microbiologist in industrial bioalcohol production before becoming a professor at York College, City College of New York, Tuoro College, and, presently, Metropolitan State University of Denver. At MSU Denver she teaches General Microbiology, Microbial Ecology, and Brewing Fermentation. She is a founding member of MSU Denver’s Brewery Operations and Brewpub Operation programs. Her active laboratory within MSU Denver’s Biology Department researches various questions related to fermentation science and extreme microbiology.