Practical application of generic growth theory and the significance of the growth curve parameters

The generic growth curve is developed by plausibility arguments based on simple growth models. Parameters of the generic curve include the maximum size, maximum specific growth rate, and a dimensionless velocity constant which can be related to metabolic efficiency in the case of nutrient-limited growth. Parameter estimates are obtained from estimates of the size and time at the point of inflection, the size and time at any other arbitrarily selected point, and the maximum size. Parameter estimates thus obtained and used as initial estimates in nonlinear least squares analysis often give rapid convergence to a minimum error mean square. [For the growth of Escherichia coli K-12 in liquid medium, the generic curve could be simplified to a form containing only three parameters: the maximum specific growth rate, the maximum size, and the time required to reach maximum size. When the bacteria were inhibited by the addition of increasing amounts of the lactoperoxidase antimicrobial factor, there was no significant change in viable counts or maximum specific growth rate, but the time required to reach maximum growth increased linearly with increasing amounts of added antimicrobial factor.] Analysis of growth in terms of the generic growth curve can be a powerful technique for finding relationships which may not be apparent from qualitative consideration of the data.