Directed Multistep Biocatalysis for the Synthesis of the Polyketide Oxytetracycline in Permeabilized Cells of Escherichia coli

We report on tailored regeneration modules for the essential cofactors ATP and NADPH as well as for SAM supply, adapted to support biocatalytic multistep synthesis of oxytetracycline (OTC) in permeabilized cells of E. coli. ATP is regenerated from ADP and AMP by the use of polyphosphate. The efficiency of this system was proven with permeabilized cells producing flaviolin. NADPH is regenerated from NADP<sup>+</sup> by oxidation of phosphonate. A constant level of 0.7 mg/L of SAM is provided by the ligation of ATP and methionine. OTC is synthesized at a rate of 2.05 ng/(h (g of the combined biocatalyst)), reaching a final concentration of 0.9 mg/L.