Figure 2.

Fermentation of glucose to succinate by genetically engineered central anaerobic metabolic pathway. Bold vertical bar means that the relative gene was inactivated. Bold arrows show overexpression. (1) The PEP-dependent glucose uptake system is replaced with ATP-dependent phosphorylation, (2) the activation of the glyoxylate pathway, (3) the knockouts of lactate (lactate dehydrogenase), (4) the knockouts of formate pathway (pyruvate formate-lyase), (5) and (6) the knockouts of acetate pathway (acetate kinase, phosphate acetyltransferase), (7) the knockouts of ethanol pathway (alcohol dehydrogenase), (8) overexpressed phosphoenolpyruvate carboxylase, (9) overexpressed malic enzyme, (10) overexpressed pyruvate carboxylase.