In order to describe the behaviour of Pseudomonas marginalis on ready-to-use vegetables, the effects of carbon and nitrogen sources on biomass profile were evaluated. First of all, experiments were carried out in synthetic medium with a multiwell analyser, using a factorial design. To establish a predictive model, a non-linear equation was developed: cell density profile was described by two Gompertz functions including yeast extract, pectin and fructose influences. Starch had little or no effect on growth rate of Ps. marginalis. Finally, validation of the mathematical model was performed with cultures in 50 ml synthetic medium flasks and with endive juice assays. In each case, a good agreement between model prediction and experimental data was found.