Mechanism of action of pulsed high electric field (PHEF) on the membranes of food-poisoning bacteria is an 'all-or-nothing' effect

Salmonella typhimurium (CRA 1005) was mole sensitive than Listeria monocyto genes (NCTC 11994) to pulsed high electric field (PHEF) treatment in distil led water (10, 15 and 20 kV/cm), 10 mM tris-maleate buffer pH 7.4 (15 kV/cm ) and model beef broth (0.75% w/v; 15 kV/cm). Sublethal injury could not be detected using a selective medium plating technique, indicating that bacte rial inactivation by PHEF may be an 'all-or-nothing' event. PHEF-induced me mbrane permeabilization resulted in increased UV-leakage and a decreased ab ility of L. monocytogenes to maintain a pH gradient. (C) 2000 Elsevier Scie nce B.V. All rights reserved.