Figure 7.

Effect of hydrogen formation rate with fixed glucose and acetate uptake. H₂ output flux was varied to examine the effect of hydrogen production on predicted formation rates for butyrate, acetone, butanol, ethanol, and biomass. Glucose and acetate uptake rates were fixed to 9.39 and 3.41 mmol/gDW/hr, respectively, and non-growth associated maintenance was set to 8.5 mmol/gDW/hr. Note that while positive ethanol formation is not depicted in the plot, FVA found ethanol and butanol production to be interchangeable, with no detrimental result to growth rate--likely because the net consumption of NADH is identical in both scenarios. Experimentally, ethanol formation happens at a slower rate than butanol formation.