A SEMICONTINUOUS CULTURE MODEL THAT LINKS CELL-GROWTH TO EXTRACELLULAR NUTRIENT CONCENTRATION

The success of the scientific studies and industrial processes based on semicontinuous culture methods requires accurate methods for estimating cell growth rates from observed cell-concentration-versus-time curves. A new logistic model for estimating cell growth in semicontinuous culture is derived. The new model can be used to estimate cell growth rates when exhaustion of a single limiting nutrient causes a cell population in semicontinuous culture to show a logistic rather than an exponential growth curve. Moreover, the new model for logistic cell growth in semicontinuous culture shows how the apparent logistic growth rate and the plateau cell concentration depend on the input nutrient concentration, N//0, and on the effective dilution rate, minus DELTA t** minus **1 ln (1 - f). Also, this model reduces to Fencl's model of exponential cell growth in semicontinuous culture when ample growth-limiting nutrient is available, i. e. , for the special case where N//n greater than greater than C//n/Y//C/////n.