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 determine d using an epi-fluorescence method in conjunction with an image analys is system. This technique provided an accurate and rapid measurement o f viability and results were found to correlate closely with the colon y-forming unit (CFU) method when used under the same conditions. In ad dition, the epi-fluorescence method proved to be more versatile in tha t viability measurements could actually be carried out at low water ac tivities (a(w)), whereas the reference CFU method required an increase in a(w).