Development of glutaric acid production consortium system with α-ketoglutaric acid regeneration by glutamate oxidase in Escherichia coli

Abstract

Glutaric acid is a C5 dicarboxylic acid that can be used as a building block for bioplastics. Although high concentrations of glutaric acid can be produced by fermentation or bioconversion, a large amount of α-ketoglutaric acid (α-KG) is necessary to accept the amine group from 5-aminovaleric acid. To decrease the demand for α-KG, we introduced l-glutamate oxidase (GOX) from Streptomyces mobaraensis in our previous system for cofactor regeneration in combination with a glutaric acid production system from 5-aminovaleric acid. To enhance glutaric acid production, critical factors were optimized such as the expression vector, pH, temperature, and cell ratio. As a result, the demand for α-KG was decreased by more than 6-fold under optimized conditions. Additionally, the effect of catalase was also demonstrated by blocking the degradation of α-KG to succinic acid because of the hydrogen peroxide. Finally, 468.5mM glutaric acid was produced from 800mM 5-aminovaleric acid using only 120mM α-KG. Moreover, this system containing davBA, gabTD-nox, and gox can be applied to produce glutaric acid from L-lysine by reusing α-KG with GOX. This improved cofactor regeneration system has a potential to apply much larger production of glutaric acid