Process Biochemistry, Vol.77, 100-105, 2019
Fermentation and purification of microbial monomer 4-amminocinnamic acid to produce ultra-high performance bioplastics
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. colt 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. coil strain producing phenylalanine ammonia lyase of the yeast Rhodotorula glutinis. The E. colt cells cultured under optimized conditions converted 4APhe to 4ACA at a rate of 0.65 g 4ACA OD600-1. 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.