Fermentation and purification of microbial monomer 4-amminocinnamic acid to produce ultra-high performance bioplastics

Abstract Aromatic amines are base materials for generating super-engineering plastics such as polyamides and polyimides. Recombinant Escherichia coli ferments 4-aminocinnamic acid (4ACA) from glucose, and it can be derived to plastics of biomass origin with extreme thermal properties. Here, we scaled-up 4ACA production by optimizing microbial fermentation processes. The initial fermentation of 4-aminophenylalanine (4APhe) using E. coli generated the papABC genes of Pseudomonas fluorescens that produced 4APhe with a volumetric mass transfer coefficient ( k L a ) of 70 h −1 in 115 L of culture broth, and 334 g of 4APhe at a final concentration of 2.9 g 4APhe L −1 . Crude 4APhe prepared from the fermentation broth was bioconverted to 4ACA by an E. coli strain producing phenylalanine ammonia lyase of the yeast Rhodotorula glutinis . The E. coli cells cultured under optimized conditions converted 4APhe to 4ACA at a rate of 0.65 g L −1 4ACA OD 600 −1 . These processes resulted in the final derivation of 4.1 g L −1 of 4ACA from glucose. The 4ACA was purified from the reaction as a hydrochloric acid salt and photodimerized to 4,4’-diaminotruxillic acid, which was polycondensed to produce bioaromatic polyimides. Large-scale 4ACA production will facilitate investigations of the physicochemical properties of biomass-derived aromatic polymers of 4ACA origin.