THE USE OF EPI-FLUORESCENCE TO DETERMINE THE VIABILITY OF SACCHAROMYCES-CEREVISIAE SUBJECTED TO OSMOTIC SHIFTS

The viability of yeast cells subjected to osmotic shifts was determined using an epi-fluorescence method in conjunction with an image analysis system. This technique provided an accurate and rapid measurement of viability and results were found to correlate closely with the colony-forming unit (CFU) method when used under the same conditions. In addition, the epi-fluorescence method proved to be more versatile in that viability measurements could actually be carried out at low water activities (a(w)), whereas the reference CFU method required an increase in a(w).