This Demonstration shows the effect of metabolic burden due to foreign protein overexpression on the growth rate of recombinant bacteria. Also, the amount of foreign protein produced at the end of the simulated batch culture is shown as a function of various parameters chosen using the sliders. By varying the value of protein expression rate before and after induction, you can see in the main plot the effect of strong, moderate, and weak induction (proportional to the amount of inducer added) at selected induction times, as well as leaky or nonleaky expression from the uninduced promoter. You can vary the initial concentrations of plasmid-free cells, as a fraction of the plasmid-containing cells, as well as the probability of generating plasmid-free cells during the growth of plasmid-containing cells; their effect on the exponential growth curves is shown in the "cell growth" plot. A major objective for repeated simulations of this interactive program is to determine the optimum combination of the parameters that will maximize the accumulated intracellular foreign protein concentration at the end of batch culture.
This Demonstration uses the structured kinetic model for recombinant bacteria developed in W. E. Bentley and D. S. Kompala, "A Novel Structured Kinetic Modeling Approach for Analysis of Plasmid Instability in Recombinant Bacterial Fermentations," Biotechnology and Bioengineering, 33, pp. 49–61 (1989). Further details and discussion of these simulations may be found in a subsequent publication by Bentley and Kompala, "Optimal Induction of Foreign Protein Expression in Recombinant Bacterial Cultures," Biochemical Engineering VI, Annals of New York Academy of Sciences 589, pp. 121–138 (1990).