Carbon Flux-Associated Redox Rebalancing By Static and Dynamic Control | AIChE

Carbon Flux-Associated Redox Rebalancing By Static and Dynamic Control

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The intracellular redox state plays an important role for the efficient production of chemicals and biofuels by microbial cell factories. However, it is difficult to achieve optimal redox rebalancing of synthetic pathways due to the sensitive responses of cellular physiology with regard to the intracellular redox state changes as well as overall carbon fluxes. Here, we propose optimal rebalancing of the intracellular redox state enables maximizing cellular performance and demonstrated using n-butanol producing E. coli as a model system. Redox rebalancing was achieved by tuning the expression level of NAD+-dependent formate dehydrogenase (fdh1 from Yeast) through rational UTR engineering. In the static control of redox state, flux of n-butanol was enhanced up to 35.4% in glucose-supplemented medium, and 44.6% in case of galactose-supplemented. Interestingly, efficient production of n-butanol required different amounts of reducing equivalents depending on the substrate. This intriguing finding was expanded to construct genetic circuits for redox rebalancing in a dynamic fashion that respond to metabolic fluxes, enabling optimize cellular performance even under various environmental conditions by the automatic redox rebalancing. Collectively, this work suggests that redox rebalancing depending on cellular demands is a key determinant for strain improvement and optimal production of chemicals and fuels can be easily achieved by the redox rebalancing along with the carbon fluxes.