Elementary mode analysis and metabolic flux analysis of L-glutamate biosynthesis byCorynebacterium glutamicum

In this study we applied elementary mode analysis and metabolic flux analysis to L-glutamate biosynthesis by Corynebacterium glutamicum GDK-9. The theoretically optimal flux distribution with the maximal L-glutamate yield and the actual flux distribution of L-glutamate production were determined, which suggested that phosphoenol-pyruvate (PEP), 2-oxoglutarate (2-OXO) and iso-citric acid (ICI) were the key nodes of L-glutamate biosynthesis. It was also indicated that the carbon-fixation reaction from CO2 had great influence on the flux distribution of the key nodes. Besides, the biosynthesis of lactate could greatly decrease the L-glutamate yield. Therefore we further developed a rational dissolved oxygen control strategy to improve the L-glutamate production by strengthening the carbon-fixation reaction from CO 2 and reducing the lactate production. Under the optimized fermentation conditions, a final L-glutamate concentration of 141 g/L was obtained and the carbon yield of L-glutamate on glucose was 81.7%.