Possible mechanism of high pressure inactivation of microorganisms

Abstract We have formulated the hypothesis that the ATPase bound to the cell membrane is strongly involved in high pressure inactivation. The stability of the membrane bound ATPase under pressure would in turn be dependent on the fluidity of the membrane. It has been postulated that cells with a more fluid membrane would be more resistant to pressure. We have confirmed this by comparing cells of Lactobacillus plantarum which differed in fluidity of the membrane. Damage of the membrane by pressure was shown by staining with propidium iodide. Leakage of ATP from the cells was observed when the cells were subjected to pressure, which was also an indication of membrane damage. ATP could not be formed after severe pressure treatment, but could after mild pressure treatment. This is also in line with the above mentioned hypothesis.