Optimization of the Biosynthesis of Butyric Acid from Glucose through the Inverted Fatty Acid β-Oxidation Pathway by Recombinant Escherichia coli Strains

The biosynthesis of butyric acid from glucose through inverted fatty acid β-oxidation by recombinant Escherichia coli strains was optimized. An increased yield of the target compound was achieved resulting from the plasmid expression of the atoB, fadB, and fadE/fabI genes in the core strain MG∆4 P_L-tesB ΔyciA (MG1655 ∆ackA-pta, ∆poxB, ∆ldhA, ∆adhE, P_L-SD_ϕ10-tesB, ∆yciA). The positive effect of enforced ATP hydrolysis on microaerobic conversion of the carbohydrate substrate to the final product by the recombinants was demonstrated. Activation of the futile cycle of pyruvate–phosphoenolpyruvate–pyruvate, due to the increased expression of the ppsA gene, ensured a marked increase in glucose consumption by the recombinants and led to an increase in the molar yield of butyric acid up to 39.5%. When the components of the H⁺-ATP synthase complex were uncoupled resulting from the deletion of atpFH genes, the molar yield of butyric acid from glucose demonstrated by the strain forming butyryl-CoA by the action of enoyl-ACP reductase FabI reached 46%.