Fig. 2

The calculated pathways from chorismate to pyruvate in the model before (A) and after (B) adding demand reactions for all carbon-containing molecules. The chorismate input flux was set at 10 mmol/gDCW/h, equal to 100 mmolC/gDCW/h as chorismate contains 10 carbon atoms. Three carbon-containing metabolites were produced in pathway A: pyruvate (3 C atoms), enterochelin (30 C) and indole (8 C). The output flux of pyruvate is only 2 mmol/gDCW/h, accounting for only 6 % of the carbon input from chorismate. The main outputs of pathway A are actually enterochelin (45 % C) and indole (44 % C). Pyruvate is just a byproduct of two reactions in the pathway, and most of the produced pyruvate is also reused through serine (dashed lines are a simplified representation of many reactions in the pathway) to produce enterochelin. Therefore, it is not reasonable to regard pathway A as converting chorismate to pyruvate. After adding demand reactions for 4-hydroxybenzoate, pathway B that contains only one main reaction in which pyruvate is a product was obtained. ichor: Isochorismate; 23ddhb: 2, 3-Dihydro-2, 3-dihydroxybenzoate; 23dhb: 2, 3-Dihydroxybenzoate; 23dhba: (2,3-Dihydroxybenzoyl)adenylate; anth: Anthranilate; pran: N-(5-Phospho-D-ribosyl)anthranilate; 2cpr5p: 1-(2-Carboxyphenylamino)-1-deoxy-D-ribulose 5-phosphate; 3ig3p: C’-(3-Indolyl)-glycerol 3-phosphate