Growth and reducing capacity of Listeria monocytogenes under different initial redox potential
Résumé
Aims: To determine the reducing capacity of Listeria monocytogenes and to highlight the effect of redox potential on its growth parameters. Methods and Results: The reducing capacity of L. monocytogenes was monitored in Brain Heart Infusion Broth media at different initial redox potential (Eh) and pH at 37 C. The effect of Eh obtained by gas flushing (air, N2 and N2-H2) or by adding potassium ferricyanide and dithiotreitol in concentration from 1 to 10 mmol l)1on L. monocytogenes growth parameters at pH 6Æ0, 7Æ0 and 8Æ0 was investigated. A total change of 539 mV (±44 mV) from an initial redox value of +330 ± 8 mV to a more negative potential in redox curves was observed resulting from L. monocytogenes growth at pH 7Æ0 at 37 C. A significant influence of pH and redox potential on L. monocytogenes lag phase of growth was shown (P < 0Æ05). Conclusions: Listeria monocytogenes exhibited longer lag phase in reducing conditions and at pH 6Æ0. The method used to modify the redox potential was shown to have no effect on growth parameters at pH 7Æ0. Significance and Impact of the Study: The provided information on the extending lag time and the possible delayed growth of this major pathogen in reducing conditions might be useful for its control in foods.