Production of (R)-(-)-mandelic acid by electrochemically driven enzyme bioreactor

Enterococcus faecalis was cultivated under oxidative conditions established by adding some oxidants. FAD and lipoic acid either stimulate the biosynthesis of benzoylformate reductase or stabilize the enzyme, while $MV^{2+}$ enhance the biosynthesis of the oxidoreductase but destabilize it. Since $MV^{2+}$ destabilize the benzoylformate reductase, substituting FAD for $MV^{2+}$ as a redox mediator would be desirable. Production of (R)-(-)-mandelic acid by a coupled reaction between the enzymatic reaction using benzoylformate reductase and the electrocatalytic reduction under the conditions of 1.5 U LiDH $ml^{-1}$, 0.2 mM FAD, and 0.3 mM $NAD^+$ is now performing.