Reactions schemes that describe the fluxes through glycolysis and the PEP/pyruvate node. Left: Case A. Growth on glycolytic PTS substrate and non-PTS substrates. State variable X represents all PTS components. Right: Case B. Growth on gluconeogenetic substrates. Values in parenthesis indicate the flux distribution during growth on acetate  in % of the acetate uptake. Main routes to PEP and pyruvate are via PckA (PEP carboxykinase) and MaeB/SfcA (malate dehydrogenase).