freeze-thaw stress response of the yeast Saccharomyces cerevisiae is growth phase specific and is controlled by nutritional state via the RAS-cyclic AMP signal transduction pathway

• Published in: Applied and Environmental Microbiology Vol. 63; no. 10; pp. 3818 - 3824
• Main Authors: Park, J.I, Grant, C.M, Attfield, P.V, Dawes, I.W
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for Microbiology 01.10.1997
• Subjects: Action of physical and chemical agents; Adaptation, Physiological; Biochemistry; Biological and medical sciences; Carbon - metabolism; Cell Cycle; Cyclic AMP - metabolism; Freezing; Fundamental and applied biological sciences. Psychology; Fungal Proteins - genetics; Fungal Proteins - metabolism; Genes, Fungal; Genes, ras; Microbiology; Mutation; Mycology; Nitrogen - metabolism; plant biochemistry; plant damage; plant health; plant physiology; ras Proteins - genetics; ras Proteins - metabolism; Saccharomyces cerevisiae; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - growth & development; Saccharomyces cerevisiae - metabolism; Signal Transduction; Stress; Temperature; Yeast; Culture medium; Oxidative stress; Microorganism growth; Yeast; Ethanol; Enzyme; Cyclic AMP; Phosphorus-oxygen lyases; Lyases; Fermentation; Fungi; Freeze thaw cycle; Adenylate cyclase; Osmotic shock; Cycloheximide; Signal transduction; Thermal shock; Production; Microorganism culture; Ascomycetes; Saccharomyces cerevisiae; Viability; Thallophyta; Cell respiration
• ISSN: 0099-2240; 1098-5336
• DOI: 10.1128/aem.63.10.3818-3824.1997

The ability of cells to survive freezing and thawing is expected to depend on the physiological conditions experienced prior to freezing. We examined factors affecting yeast cell survival during freeze-thaw stress, including those associated with growth phase. requirement for mitochondrial functions, and prior stress treatment(s), and the role played by relevant signal transduction pathways. The yeast Saccharomyces cerevisiae was frozen at -20 degrees C for 2 h (cooling rate, less than 4 degrees C min-1) and thawed on ice for 40 min. Supercooling occurred without reducing cell survival and was followed by freezing, loss of viability was proportional to the freezing duration, indicating that freezing is the main determinant of freeze-thaw damage. Regardless of the carbon source used, the wild-type strain and an isogenic petite mutant ([rho0]) showed the same pattern of freeze-thaw tolerance throughout growth, i.e., high resistance during lag phase and low resistance during log phase, indicating that the response to freeze-thaw stress is growth phase specific and not controlled by glucose repression. In addition, respiratory ability and functional mitochondria are necessary to confer full resistance to freeze-thaw stress. Both nitrogen and carbon source starvation led to freeze-thaw tolerance. The use of strains affected in the RAS-cyclic AMP (RAS-cAMP) pathway or supplementation of an rca1 mutant (defective in the cAMP phosphodiesterase gene) with cAMP showed that the freeze-thaw response of yeast is under the control of the RAS-cAMP pathway. Yeast did not adapt to freeze-thaw stress following repeated freeze-thaw treatment with or without a recovery period between freeze-thaw cycles, nor could it adapt following pretreatment by cold shock. However, freeze-thaw tolerance of yeast cells was induced during fermentative and respiratory growth by pretreatment with H2O2, cycloheximide, mild heat shock, or NaCl, indicating that cross protection between freeze-thaw stress and a limited number of other types of stress exists.