Yeast cell mortality related to a high-pressure shift: occurrence of cell membrane permeabilization

• Autores: M. Hayert, P. Gervais, J.-M. Perrier-Cornet
• Localización: Journal of applied microbiology, ISSN 1364-5072, Vol. 87, Nº 1, 1999, págs. 1-7
• Idioma: inglés
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• Resumen

  • The shrinkage of yeast cells caused by high‐pressure treatment (250 MPa, 15 min) was investigated using direct microscopic observation. A viable staining method after treatment allowed the volume variation of two populations to be distinguished: an irreversible volume decrease (about 35% of the initial volume) of pressure‐inactivated cells during pressure holding time, and viable cells, which were less affected. A mass transfer was then induced during high‐pressure treatment. Causes of this transfer seem to be related to a pressure‐induced membrane permeabilization, allowing a subsequent leakage of internal solutes, where three ions (Na+, K+ and Ca2+), plus endogenous glycerol, were verified. This glycerol leakage was found to occur after yeast pressurization in a medium having low water activity, although the yeast was not inactivated. All these observations lead to the hypothesis that pressure‐induced cell permeabilization could be the cause of yeast inactivation under pressure.