An aromatic compound para-aminobenzoic acid (PABA) has a great potential to serve as a raw material for medicines or polymers. Currently, it is manufactured by chemical synthesis from fossil resources. With the recent increases in environmental consciousness, there is a growing interest in the production of PABA from renewable resources by fermentation. In this study, Corynebacterium glutamicum was genetically engineered to produce PABA from glucose. During the fermentation, a large amount of byproduct was detected. Surprisingly, it was formed non-biologically from glucose and PABA, and an acid treatment enabled to salvage PABA. Then, a strain overexpressing both pabAB of Corynebacterium callunae and pabC of Xenorhabdus bovienii was constructed and cultured for 48 h under a fermenter-controlled condition. The PABA concentration reached to about 300 mM (43 g/L) after the acid treatment. It was the highest concentration ever reported.
