Enhancement of alpha,omega-Dicarboxylic Acid Production by the Expression of Xylose Reductase for Refactoring Redox Cofactor Regeneration

Abstract

The production of alpha,omega-dicarboxylic acids (DCAs) by whole-cell biocatalysis is often limited by cofactor regeneration. Here, co-oxidation pathway genes (monooxygenase, alcohol dehydrogenase, and aldehyde dehydrogenase) were coexpressed with a xylose reductase (XR) gene to regenerate cofactors in an engineered Escherichia coli strain that cometabolizes glucose and xylose. The resulting strain exhibited a 180% increase in DCA production compared with the control strain without XR, and produced xylitol in the presence of xylose. Expression of monooxygenase and XR without other co-oxidation pathway genes resulted in an additional increase in tetradecanedioic acid concentration and a substrate conversion of 95%, which was 198% higher than that associated with the control strain. The expression of XR helped the system to regenerate and balance the cofactors thereby achieving maximum substrate conversion efficiency. It could serve as an efficient platform for the industrial production of alpha,omega-DCAs.