Production of P3HB by recombinant strains of E. coli presenting cofactor swapping in glucose 6-phosphate dehydrogenase (G6PDH) and isocitrate dehydrogenase (ICDH) was evaluated. The P3HB produced by ICDHNAD mutant was a slightly lower than the wild type strain, suggesting a low contribution of Krebs cycle to supply NADPH for P3HB production. Surprisingly the mutant G6PDHNAD produced higher amounts of P3HB than the wild type strain, suggesting a limited supply of acetyl-CoA in E. coli for PHB production.