Fig. 2

MDF analysis of the TCA cycle (a and b) and ethanol production (c) in C. thermocellum. a Overview of the TCA cycle. The reaction between malate and oxaloacetate is catalyzed by malate dehydrogenase, which was found to be the limiting step in the pathway. b MDF as a function of pH, as calculated for the TCA cycle (‘Standard TCA’), for an oxaloacetate concentration of 10 nM (‘[OAA] = 10 nM’), and with oxaloacetate channeling included (‘OAA channeling’). c Ethanol production pathway for the best-performing strain with three interventions. Suggested interventions are shown in green while the native reaction is shown in red. For all the panels, metabolites are shown in blue. G1p, glucose-1-phosphate; g6p, glucose-6-phosphate; f6p, fructose-6-phosphate; fdp, fructose 1,6-bisphosphate; g3p, glycerol-3-phosphate; 13dpg, 3-phosphoglyceroyl phosphate; 3 pg, 3-phosphoglycerate; 2 pg, glycerate-2-phosphate; pep, phosphoenolpyruvate; pyr, pyruvate; accoa, acetyl-CoA; acald, acetaldehyde; etoh, ethanol