[Mathematical model of tryptophan synthesis and excretion into the environment by E. coli cells]

A quantitative kinetic model is suggested for the auto-regulated tryptophan synthesis by E. coli trp-operon system and for tryptophan excretion from the cell mediated by transport systems. Applications of the model for the calculation of several parameters characterizing tryptophan metabolism are considered. In order to explain experimental data it is suggested that a system of tryptophane excretion from the cell exists which is induced by high tryptophan concentrations. The rate of tryptophan excretion was studied as a function of various genetic effects (derepression or reduction of retroinhibition) as well as of changes in intracellular concentrations of substrates of tryptophan synthesis (chorismic acid and serine). Possible ways of making the cell to excrete markedly higher quantities of tryptophan without changing the genotype are discussed.