Key enzymatic reactions in the production of pyruvate by Escherichia coli strains. Enzymes: 1, PEP carboxylase, 2, PEP synthase, 3, lactate dehydrogenase, 4, pyruvate oxidase, 5, pyruvate formate lyase, 6, pyruvate dehydrogenase complex, 7, acetyl-CoA synthetase, 8, acetate kinase, 9, phosphotransacetylase.