Metabolic engineering of Escherichia coli to high efficient synthesis phenylacetic acid from phenylalanine.

Phenylacetic acid (PAA) is a fine chemical with a high industrial demand for its widespread uses. Whereas, microorganic synthesis of PAA is impeded by the formation of by-product phenethyl alcohol due to quick, endogenous, and superfluous conversion of aldehydes to their corresponding alcohols, which resulted in less conversation of PAA from aldehydes. In this study, an Escherichia coli K-12 MG1655 strain with reduced aromatic aldehyde reduction (RARE) that does duty for a platform for aromatic aldehyde biosynthesis was used to prompt more PAA biosynthesis. We establish a microbial biosynthetic pathway for PAA production from the simple substrate phenylalanine in E. coli with heterologous coexpression of aminotransferase (ARO8), keto acid decarboxylase (KDC) and aldehyde dehydrogenase H (AldH) gene. It was found that PAA transformation yield was up to ~94% from phenylalanine in E. coli and there was no by-product phenethyl alcohol was detected. Our results reveal the high efficiency of the RARE strain for production of PAA and indicate the potential industrial applicability of this microbial platform for PAA biosynthesis.