Growth characteristics of Enterobacter sakazakii used to develop a predictive model

Abstract

A mathematical model was developed for predicting the growth rate of Enterobacter sakazakii in tryptic soy broth medium as a function of the combined effects of temperature (5, 10, 20, 30, and 40 degrees C), pH (4, 5, 6, 7, 8, 9, and 10), and the NaCI concentration (0, 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10%). With all experimental variables, the primary models showed a good fit (R-2 = 8965 to 0.9994) to a modified Gompertz equation to obtain growth rates. The secondary model was 'n specific growth rate= -0.38116+(0.01281*Temp)+(0.07993*pH)+(0.00618*NaCl)+(-0.00018*Temp(2))+(-0.00551*pH')+(-0.00093*NaCl) +(0.00013*Temp*pH)+(-0.00038*Temp*NaCl)+(-0.00023*pH*NaCl)'. This model is thought to be appropriate for predicting growth rates on the basis of a correlation coefficient (r) 0.9579, a coefficient of deten-nination (W) 0.91, a mean square error 0.026, a bias factor 1.03, and an accuracy factor 1.13. Our secondary model provided reliable predictions of growth rates for E sakazakii in broth with the combined effects of temperature, NaCl concentration, and pH.