Metabolic engineering of Escherichia coli for the production of 3-aminopropionic acid

Abstract

A novel metabolic pathway was designed for the production of 3-aminopropionic acid (3-AP), an important platform chemical for manufacturing acrylamide and acrylonitrile. Using a fumaric acid producing Escherichia calf strain as a host, the Corynebacterium glutamicum panD gene (encoding L-aspartate-alpha-decarboxylase) was overexpressed and the native promoter of the aspA gene was replaced with the strong me promoter, which allowed aspartic acid production through the aspartase-catalyzed reaction. Additional overexpression of aspA and ppc genes, and supplementation of ammonium sulfate in the medium allowed production of 3.49 g/L. 3-AP The 3-AP titer was further increased to 3.94 g/L by optimizing the expression level of PPC using synthetic promoters and RES sequences. Finally, native promoter of the acs gene was replaced with strong trc promoter to reduce acetic acid accumulation. Fed-batch culture of the final strain allowed production of 32.3 g/L 3-AP in 39 h.