INFLUENCE OF SALAD CONSTITUENTS ON GROWTH OF PSEUDOMONAS-MARGINALIS -A PREDICTIVE MICROBIOLOGY APPROACH

In order to describe the behaviour of Pseudomonas marginalis on ready- to-use vegetables, the effects of carbon and nitrogen sources on bioma ss profile were evaluated. First of all, experiments were carried out in synthetic medium with a multiwell analyser, using a factorial desig n. To establish a predictive model, a non-linear equation was develope d: cell density profile was described by two Gompertz functions includ ing yeast extract, pectin and fructose influences. Starch had little o r no effect on growth rate of Ps. marginalis. Finally, validation of t he mathematical model was performed with cultures in 50 ml synthetic m edium flasks and with endive juice assays. In each case, a good agreem ent between model prediction and experimental data was found.