Utilizing electrochemical bioreactors for efficient chemical and biological applications

Abstract

Industrial enzymatic reactions that require 1,4-NAD(P)H₂ to perform redox transformations often require convoluted coupled enzyme regeneration systems to regenerate 1,4-NAD(P)H₂ from NAD(P) and recycle the cofactor for as many turnovers as possible. Renewed interest in recycling the cofactor via electrochemical means is motivated by the low cost of performing electrochemical reactions, easy monitoring of the reaction progress, and straightforward product recovery. However, direct electrochemical cofactor regeneration methods invariably produce adventitious reduced cofactor side products which result in unproductive loss of input NAD(P). I will explore various strategies for mitigating adventitious product formation by electrochemical cofactor regeneration systems and offer insight as to how a successful electrochemical bioreactor system could be designed to engineer efficient 1,4-NAD(P)H₂-dependent enzyme reactions of interest to the industrial biocatalysis community. Further, I will explore the utility of an electrochemical bioreactor for delivering external reducing equivalents to an engineered strain of bacteria for improving carbon efficiency and product yield compared to cells that have not been provided external reducing equivalents.