Modeling microbial kinetics as a function of temperature: identification of the growth/inactivation interface

A previous implementation of dynamic experiments for the estimation of the parameters of the Cardinal Temperature Model with Inflection (CTMI), which describes the temperature effect on the microbial growth rate, revealed that the maximum growth temperature (Tmax) can only be estimated accurately when temperatures close to the true Tmax are included. As such, a reliable Tmax estimate is required at the beginning of the OED/PE implementation. Here, alternative experiments in which the temperature exceeds the growth/inactivation interface are evaluated.Results from the simulation study show that the accuracy and reliability of the Tmax estimate depends on the selected temperature profile. A very accurate and realistic Tmax value is obtained from experiments with an initial temperature slightly lower than the true Tmax. When the dynamic temperature starts at temperatures above Tmax, a larger uncertainty and variability is observed. From this, it can be concluded that information with respect to growth at temperatures close to Tmax is required for an accurate and reliable Tmax estimate.In a second step, two dynamic temperature profiles are implemented in a computer controlled bioreactor. The experimental data do not result in an accurate and reliable estimation of Tmax. Additional dynamic experiments are required to evaluate the proposed experimental set-up.