Production of 3-Aminopropionic Acid, a Precursor for Nylon-3 Synthesis By a Metabolically Engineered Escherichia coli
Metabolic engineering strategies were taken to produce 3-aminopropionic acid (3-AP), an important platform chemical for manufacturing acrylamide and acrylonitrile, in Escherichia coli. Using a fumaric acid producing E. coli strain as a host, the C. glutamicum panD gene (encoding L-aspartate-α -decarboxylase) was overexpressed and the native promoter of the aspA gene was replaced with the strong trc promoter to strengthen the aspartase-catalyzed reaction. The aspA and phosphoenolpyruvate carboxylase (ppc) genes were additionally overexpressed, and the ammonium sulfate was supplemented in the medium, which resulted in the production of 3.49 g/L 3-AP. Optimization of PPC expression level by using synthetic promoter and RBS sequences increased the titer upto 3.94 g/L. The amount of accumulated acetic acid was decreased by replacing the native promoter of the acs gene with strong trc promoter and the fed-batch culture of this final strain produced 32.3 g/L of 3-AP in 39h with an overall yield and productivity of 0.135 g 3-AP/g glucose and 0.828 g/L/h, respectively. (This work was supported by the Technology Development Program to Solve Climate Changes on Systems Metabolic Engineering for Biorefineries from the Ministry of Science, ICT and Future Planning (MSIP) through the National Research Foundation (NRF) of Korea (NRF-2012M1A2A2026556 and NRF-2012M1A2A2026557)).