Model for bacterial culture growth rate throughout the entire biokinetic temperature range

TLDR

The classic square‑root model of Ratkowsky et al. for sub‑optimal bacterial growth was expanded to span the entire biokinetic temperature range. The new nonlinear regression model, with two parameters defining minimum and maximum temperature limits, fits bacterial growth data across all tested strains, yielding nearly unbiased, normally distributed least‑squares estimates and demonstrating robust performance for 30 strains.

Abstract

The "square-root" relationship proposed by Ratkowsky et al. (J. Bacteriol. 149:1-5, 1982) for modeling the growth rate of bacteria below the optimum growth temperature was extended to cover the full biokinetic temperature range. Two of the four parameters of this new nonlinear regression model represent minimum and maximum temperature bounds, respectively, for the predicted growth of the culture. The new model is easy to fit and has other desirable statistical properties. For example, the least-squares estimators of the parameters of the model were almost unbiased and normally distributed. The model applied without exception to all bacterial cultures for which we were able to obtain data. Results for 30 strains are reported.