Sakun A. Analysis of efficiency of cell suspension cryopreservation with constant and variable cooling rates

The research object is cryopreservation of yeast-like fungi S. serevisiae. The aim of the research were designing and experimental confirmation of quantitative model of yeast-like fungi S. serevisiae suspension cryodamage in "DMSO (10 at.%) - 0,135М NaCl - water" solution at the linear and nonlinear cooling rates at the crystallization stage. Research methods were volumetricity, light microscopy, thermography, Koch plate method, theoretical modeling. Results can be used for development of cryopreservation methods of microorganisms with the use of the linear and nonlinear freezing rates. Scientific novelty consist in the firstly specified quantitative model of cryopreserved cell cryodamage at the stage of crystallization; there is firstly shown, that the mechanism of cryoprotective action of the rapid two-stage cooling at principle does not differ from the optimal from standpoint of two-factor theory of cryodamage linear rate cooling; the optimal nonlinear cooling rate of yeast cells S. serevisiae is defined; the activation energy values of processes for water and cryoprotectants penetration through S. serevisiae plasma membrane are determined; it is shown, that 1,2-PD affects S. serevisiae plasma membrane, lowering the activation energy for water molecules penetration through it.