Applied Biochemistry and Biotechnology, Vol.172, No.8, 3989-4001, 2014
Improvement of the Production Efficiency of L-(+)-Tartaric Acid by Heterogeneous Whole-Cell Bioconversion
An Escherichia coli-engineered bacterium with cis-epoxysuccinate hydrolase (ESH) activity was used to catalyze the stereospecific hydrolysis of cis-epoxysuccinic acid to l-(+)-tartaric acid. The effect of the substrate composition on the production efficiency of l-(+)-tartaric acid was investigated. Based on the sodium-type homogeneous substrate system, a heterogeneous substrate system, composed of 1.2 M sodium-type substrate and 1.8 M calcium-type substrate, was designed to improve ESH catalytic efficiency. After process optimization, a catalytic efficiency of 9.37 x 10(-3) g U-1 h(-1) was obtained with fed-batch mode in the heterogeneous substrate system, about a twofold increase compared to the traditional bioconversion process with Nocardia tartaricans cells. The scale-up tests were carried out in a 15-m(3) stirred tank reactor, which indicated that the heterogeneous substrate system had great application prospect for the l-(+)-tartaric acid industrial production.