Vitrification and ultra-rapid laser warming of yeast Saccharomyces cerevisiae

Abstract

BACKGROUND As fundamental model organisms, yeasts have been used for the study and understanding of cryopreservation and freezing damage mechanisms, in particular Saccharomyces cerevisiae. OBJECTIVE As cryopreservation success requires optimization of the cooling and warming rates, the objective was to test how ultra-rapid warming could improve yeast cell cryopreservation. MATERIALS AND METHODS S. cerevisiae cells were exposed to concentrations of vitrification solutions containing a combination of permeating and non-permeating cryoprotectants (EAFS) and to a simple 1 M sucrose solution prior to vitrification (cooling rate 69,000°C min-1). Cells were then warmed ultra-rapidly with a laser (warming rate 107°C min-1). RESULTS When using a vitrification solution (0.33xEAFS) survival was 80 ± 16%. When using only a non-permeating solute (1 M sucrose) for cryoprotection, the results were slightly lower, viz. 61 ± 26 %. CONCLUSION These results add information to the study of the effect of numerous cooling and warming rates for baker´s yeast cryopreservation and provide further examples of the application of vitrification and ultra-fast laser warming. Ultra-rapid warming seems to be applicable to a wide range of cells and tissues from diverse species.