Figure 1

Characteristics of the different glucose fermentations for Clostridium butyricum CWBI 1009 performed under unregulated-pH and at fixed pH 7.3 and 5.2. (A, B, C) Growth curve (OD) and pH. (D, E, F) Hydrogen production rate (L/h) and cumulative hydrogen production (L) profiles. (G, H, I) Glucose utilisation and profiles of soluble metabolites (mM). The error bars refer to the three independent replicate experiments. Fermentations were performed in 20-L batch bioreactors with glucose as a substrate (10 g/L for unregulated-pH fermentations and 5 g/L for fixed-pH fermentations).