Yeast cell mortality related to a high-pressure shift: occurrence of cell membrane permeabilization.
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.
Perrier-Cornet
J M
JM
Laboratoire de Génie des Procédés Alimentaires et Biotechnologiques, E.N.S.B.A.N.A., Dijon, France.
Hayert
M
M
Gervais
P
P
D002118:Calcium / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000502:physiology*; D005990:Glycerol / Q000378:metabolism; D006874:Hydrostatic Pressure; D017136:Ion Transport; D011188:Potassium / Q000378:metabolism; D012440:Saccharomyces / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000502:physiology; D012964:Sodium / Q000378:metabolism; D013696:Temperature
D012964:Sodium; D005990:Glycerol; D011188:Potassium; D002118:Calcium