Metabolic flux distribution for the optimized production of L-glutamate

A comprehensive metabolic network was proposed for glutamic acid bacteria and used in a stoichiometrically based flux balance model for L-glutamate production. Theoretical metabolic pathways leading to optimized glutamate overproduction were determined for several specific cell growth rates; variation in the fluxes was obtained. The off-line extracellular analyses throughout the batch fermentation with Brevibacterium flavum showed the accumulation of arginine, aspartate, lysine, alanine, proline, lactate, re alpha-ketoglutarate, succinate, pyruvate, and gluconate in the medium in addition to glutamate. Metabolic flux distributions in the cells throughout the fermentation were determined using the model in combination with the extracellular analyses of the metabolites. The flux distribution maps showed that the cells utilized the TCA cycle in part whereas the glyoxylate bypass was active throughout the fermentation. The results also indicated with the phosphate pentose shunt played an important role in the glutamate fermentation. These diversions in the pathways and certain metabolic reactions depending on the fermentation periods and conditions are also presented in this paper. (C) 1998 Elsevier Science Inc.