Compréhension des mécanismes de l'inactivation cellulaire par les hautes pressions hydrostatiques et les basses températures

Abstract : The aim of this work was to understand the effects of high hydrostatic pressure (HHP) and low temperature on different cell models: bacteria, yeast, leukemia cells, spheroplasts, lipid vesicles. The viability of cells subjected to cold stress was first assessed, through long-term supercooling experiments (up to 71 days), versus freeze-thawing stress. Results showed that cells could be inactivated by the only action of sub-zero temperature, that is, without any water crystallization. The effects of HHP at room temperature were then studied as a function of cell hydration. We highlighted the crucial role of water in determining cellular damage under pressure. The combined effects of HHP and low temperature on cells were studied. Results showed a synergistic interaction between cold and HHP in their effects on microbial inactivation at pressures in the range of 100 to 300 MPa with an aw of 0.992. However, at pressures greater than 300 MPa, this trend was reversed, and cold counteracted the inactivation effect of pressure. When the amount of water in the cell suspension was increased, the synergistic effect was enhanced. Conversely, when the aw was decreased by the addition of solute to the cell suspension, the baroprotective effect of subzero temperature increased sharply. These results support the argument that water compression is involved in the mechanisms of HHP inactivation of cells. From a thermodynamic point of view, the mechanical energy transferred to the cell during the pressure treatment can be characterized by the change in volume of the system, which depends on the water quantity in the cytoplasm. The consequences of cell volume compression at the cellular level were characterized through the assessment of metabolic activity, the study of cell membrane structure and integrity and the visualization of cell shape and ultrastructure.
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Contributor : Marwen Moussa <>
Submitted on : Thursday, December 21, 2017 - 5:36:04 PM
Last modification on : Friday, December 29, 2017 - 1:01:09 AM

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  • HAL Id : tel-01661728, version 1

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Marwen Moussa. Compréhension des mécanismes de l'inactivation cellulaire par les hautes pressions hydrostatiques et les basses températures. 2009. ⟨tel-01661728⟩

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