Effects of High Pressure on Inactivation Kinetics and Events Related to Proton Efflux in Lactobacillus plantarum

Abstract

Knowledge of the mechanism of pressure-induced inactivation of microorganisms could be helpful in defining an effective, relatively mild pressure treatment as a means of decontamination, especially in combination with other physical treatments or antimicrobial agents. We have studied the effect of high pressure on Lactobacillus plantarum grown at pH 5.0 and 7.0. The classical inactivation kinetics were compared with a number of events related to the acid-base physiology of the cell, i.e., activity of F0F1ATPase, intracellular pH, acid efflux, and intracellular ATP pool. Cells grown at pH 5.0 were more resistant to pressures of 250 MPa than were cells grown at pH 7.0. This difference in resistance may be explained by a higher F0F1 ATPase activity, better ability to maintain a ΔpH, or a higher acid efflux of the cells grown at pH 5.0. After pressure treatment at 250 MPa, the F0F1 ATPase activity was decreased, the ability to maintain a ΔpH was reduced, and the acid efflux was impaired. The ATP pool increased initially after mild pressure treatment and finally decreased after prolonged treatment. The observations on acid efflux and the ATP pool suggest that the glycolysis is affected by high pressure later than is the F0F1 ATPase activity. Although functions related to the membrane-bound ATPase activity were impaired, no morphological changes of the membrane could be observed.

Protective effect of calcium on inactivation ofEscherichia coliby high hydrostatic pressure

“…At ambient pressure, intracellular concentrations of metal ions are maintained below toxic levels by the low passive permeability of cell membranes and by the activity of ion efflux systems (Nies and Silver 1995). As pressure can result in disruption of membrane integrity (Shimada et al 1993;Chilton et al 1997), inhibition of cationtransporting membrane proteins (Macdonald 1984), or depletion of cellular energy required for active efflux (Wouters et al 1998), cells are expected to accumulate external cations on pressure exposure. It seems that baroprotection by external Ca 2+ is also mediated by an elevated cellular Ca 2+ content rather than by the presence of external Ca 2+ as such ( Table 3).…”

Microbial inactivation by new technologies of food preservation

“…The loss of function of some proteins including the F 1 – F 0 ATPase or multidrug efflux pumps has also been described (Smelt et al. 1994; Wouters et al. 1998; Molina‐Hoppner et al.…”

Barotolerance is inducible by preincubation under hydrostatic pressure, cold-, osmotic- and acid-stress conditions in Lactobacillus sanfranciscensis DSM 20451T

“…Hydrostatic pressure treatment is used for preservation purposes in food technology (Knorr 1999) and represents an exceptional stimulus for most mesophilic bacteria. Pressure was shown to induce multiple changes in physiology (Wouters et al 1998;Korakli et al 2002), protein expression (Welch et al 1993;Drews et al 2002;Wemekamp-Kamphuis et al 2002) and also transcription (Sato et al 1995;Ehrmann et al 2001). It causes cell injury (Ulmer et al 2002) and finally cell death (Vogel et al 2002a).…”