Influence of cooling rate on Saccharomyces cerevisiae destruction during freezing: unexpected viability at ultra-rapid cooling rates

• Published in: Cryobiology 2003-02, Vol.46 (1), p.33-42
• Main Authors: Dumont, Frédéric, Marechal, Pierre-André, Gervais, Patrick
• Format: Article
• Language: English
• Subjects: Action of physical and chemical agents; Biological and medical sciences; Biotechnology; Cell viability; Chemical and Process Engineering; Cryopreservation; Cryoprotective Agents - pharmacology; Culture Media; Engineering Sciences; Freezing; Fundamental and applied biological sciences. Psychology; Intracellular Fluid; Life Sciences; Microbiology; Mycology; Osmotic Pressure; Saccharomyces cerevisiae; Saccharomyces cerevisiae - cytology; Saccharomyces cerevisiae - drug effects; Thermodynamics; Time Factors; Ultra-rapid cooling rate
• ISSN: 0011-2240; 1090-2392
• DOI: 10.1016/S0011-2240(02)00161-X

The purpose of this work was to study cell viability as a function of cooling rate during freezing. Cooling rate strongly influences the viability of cells during cold thermal stress. One of the particularities of this study was to investigate a large range of cooling rates and particularly very rapid cooling rates (i.e., faster than 20 000 °C min −1). Four distinct ranges of cooling rates were identified. The first range (A ′) corresponds to very slow cooling rates (less than 5 °C min −1), and results in high cell mortality. The second range (A) corresponds to low cooling rates (5–100 °C min −1), at which cell water outflow occurs slowly and does not damage the cells. The third range (B) corresponds to rapid cooling rates (100–2000 °C min −1), at which there is competition between heat flow and water flow. In this case, massive water outflow, which is related to the increase in extracellular osmotic pressure and the membrane-lipid phase transition, can cause cell death. The fourth range (C) corresponds to very high cooling rates (more than 5000 °C min −1), at which the heat flow is very rapid and partially prevents water exit, which seems to preserve cell viability.