(471c) Transcription Modulation of Recombinant DNA Protein Production in a New Escherichia Coli Mutant by Using Various Inducer-Feeding Profiles

The transcription in a new Escherichia coli mutant isolated through a long term glycerol chemostat and producing a recombinant DNA protein was modulated through inducer titration to maximize the protein production. Experiments were conducted to determine the parameters of a mathematical model which in turn is used to evaluate several induction strategies. In the model the cells are divided into two groups growing at different rates. We defined a parameter α as the fraction of fully induced cells and study the effect of its variation on the production of recombinant DNA protein on the newly isolated Escherichia coli mutant. Four cases are described here: the first one is the use of a constant α throughout the whole fermentation. The target protein production was calculated when the fermentation is performed with α varying from no induction (α = 0) to induction of the whole population (α = 1). The second case studied is the variation of αduring the fermentation following a linear profile passing through the point of maximum induction (α =1) at the final moment of fermentation. In this case the parametric factor is the slope (m) of the straight line defining αThe third case studied is the variation of α, again following a linear profile passing through different induction times and ending at α = 1 and a time before the fermentation finishes. In this case two parameters were manipulated, the slope m of the linear profile and the final profile time. The four case studied is the exponential variation of α. The maximum recombinant DNA protein production for each case has been evaluated