The process of L-Tryptophan fermentation by E. coli TRTH/pSV-709 was investigated, and the result showed that there was a large number of byproduct (acetic acid) in the broth. The effect of acetic acid on L-Tryptophan fermentation was studied by experiments with addition of acetic acid. The results showed that 2 g/L acetic acid could inhibit the growth of L-Tryptophan-producing bacteria and L-Tryptophan production. The mechanism of production of acetic acid was studied. Several strategies including dissolved oxygen regulation, suitable concentration of initial glucose determination, glucose-limited pulse fed-batch and the specific growth rate regulation were applied to reduce the generation of acetic acid. Under the optimal condition, the concentration of acetic acid was decreased by 51.35% compared with that under original condition. Biomass and yield of L-Tryptophan were increased by 51.07% and 46.54% respectively, which accessed high cell density cultivation.
