PREDICTIVE MODELING OF GROWTH OF STAPHYLOCOCCUS-AUREUS - THE EFFECTS OF TEMPERATURE, PH AND SODIUM-CHLORIDE

The growth responses of Staphylococcus aureus as affected by NaCl conc entration, pH value and storage temperature were studied in laboratory medium. Growthcurves at concentrations of NaCl in the range 0.5-13.5% (w/v), pH values in the range 4.0-7.0 and storage temperatures in the range 10-30 degrees C were fitted using the Gompertz routine and the derived parameters modelled. Growth curves could then be regenerated f or any set of conditions within the matrix studied and values for grow th rate, generation time, lag time and time to 1000-fold increase pred icted. The model was validated against data from the literature and wa s found to give realistic estimates of generation time for media and a range of foods including milk, cheese, starch-based foods and cooked m eats but not for mayonnaise or Wiltshire bacon. All predictions were c onsistently 'fail-safe'.