Influence of strain and trisodium phosphate concentration on growth parameters of Listeria monocytogenes in vitro

Aims: The present study was conducted to determine the influence of strain and trisodium phosphate (TSP) concentration in the growth of Listeria monocytogenes in vitro. Methods and Results: Three strains (ATCC 11916, 64d, isolated from chicken meat, and M2-5b, a clinical animal isolate) were inoculated in broth with 0, 0.5, 1 and 1.5% (w/v) of TSP. The shortest lag phase and highest maximum rate of growth (mu) were obtained in the presence of 0.5% TSP. In contrast, the highest lag phase and lowest mu were obtained with 1.5% TSP. For each TSP concentration, significant differences (P < 0.05) in lag phase and <mu> of the three L. monocytogenes strains were observed. Conclusions: The behaviour of L. monocytogenes is significantly influenced by both the origin of the strain and the salt concentration. Significance and Impact of the Study: Our results indicate the importance of choosing an adequate TSP concentration for the decontamination of foods, because low concentrations could favour the growth of L. monocytogenes.