L. L. CHAN (1), S. Saldi (1), D. Driscoll (2), D. Kuksin (1); (1)
Nexcelom Bioscience, Lawrence, MA, U.S.A.; (2) Avery Brewing Company,
Boulder, CO, U.S.A.
Poster
Saccharomyces cerevisiae, or yeast, has been an essential
component for the production of beer for centuries. The viability and
vitality of yeast during standard brewing processes is especially
important for proper cell growth, consistent production of flavor, and
optimal yield for fermentation. Traditional methods for yeast viability
measurement depend on mainly manual counting of methylene blue-stained
yeast cells in a hemacytometer. However, this method can be
time-consuming and has user-dependent variations. In recent years,
fluorescent viability and vitality stains have become widely used for
flow and image-based cytometry methods. Specifically for image
cytometry, it has been previously demonstrated for rapid yeast
concentration and viability measurements. In this work, we demonstrate
the capability of cellometer vision image cytometry to measure yeast
viability and vitality, validating the methods against methylene blue.
Various fluorescent stains were employed for viability and vitality
measurement, such as nucleic acid stains (PI, EB, 7-AAD, and DAPI);
membrane potential, intracellular, and enzymatic stains (oxonol, MgANS,
and CFDA-AM); and dual-fluorescent stains (AO/PI and CFDA-AM/PI). In
addition, we performed a time-course viability and vitality study to
compare the physiological changes in lager and ale yeast in order to
understand yeast behavior during a standard fermentation process.
Leo Chan currently serves as the technology R&D manager at
Nexcelom Bioscience LLC, Lawrence, MA. His research involves the
development of instruments and applications for the Cellometer image
cytometry system for detection and analysis of yeasts used in brewing
and biofuel industries. He is a member of the Master Brewers Association
of the Americas. He received his B.S., M.S., and Ph.D. degrees in
electrical and computer engineering from the University of Illinois at
Urbana-Champaign (2000–2008).
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