Fig. 1.

The PDHC-PTA-ACKA pathway: Glucose and serine (the preferred sugar and amino acid carbon sources of E. coli) are metabolized to pyruvate. The pyruvate is converted to acetyl-CoA through the action of pyruvate dehydrogenase complex (PDHC). The acetyl-CoA is converted to acetyl-P by phosphotransacetylase (PTA) and the acetyl-P is converted to acetate by acetate kinase (ACKA). HS-CoA, coenzyme A; NAD+ and NADH, oxidized and reduced forms of nicotinamide adenine dinucleotide; Pi, inorganic phosphate.