Fig 1.

General metabolic network of the central carbon metabolism of lactobacilli. Extracellular substrates and products are underlined. G6P, glucose 6-phosphate; F6P, fructose 6-phosphate; FbP, fructose 1:6-bisphosphate; DHAP, dihydroxyacetone phosphate; GAP, glyceraldehyde 3-phosphate; Pyr, pyruvate; AcP, acetylphosphate; AcCoA, acetyl-CoA; OAA, oxaloacetate; X5P, xylulose 5-phosphate. As major metabolic routes, the Embden-Meyerhof-Parnas pathway (EMP), the phosphoketolase pathway (PPK), and citrate metabolism are considered. The different transport systems for glucose and fructose uptake by L. plantarum (dashed arrows) and L. fermentum (solid arrows) are also considered. To facilitate flux calculation, it is assumed that in either case fructose enters the EMP pathway at the level of fructose 6-phosphate.