Modelling the effects of glucose feeding on a recombinant E-coli fermentation

A simple unstructured model is described and compared with experimental dat a for fed-batch fermentations. The process studied is typical of the most c ommon industrial recombinant fermentation in which temperature induced E. c oli produces high yields of a heterologous protein (4 g met-asp-Bovine Soma totropin/l) using a complex peptone feed and a glucose feed. The model accu rately predicts the effect of glucose feeding and shows that there is an op timal glucose feedrate to maximize productivity. At higher glucose feedrate s, acetate levels become inhibitory and at lower levels glucose starvation occurs. The model is novel since it combines terms for acetate production a nd inhibition, effect of peptone feeding and temperature induction into a s ingle relatively simple unstructured model. However the present model is un able to predict the effect of induction at different cell densities and rea sons for this are suggested.