Figure 4.

Thermodynamic energy of three propionate degrading reactions (from Table 1), normalised per propionate, at different ambient H₂ pressures. Each reaction produces H₂ as a byproduct, and the line type indicates the reaction stoichiometry between the propionate and hydrogen (as shown in the legend). The conditions used to calculate the reaction thermodynamics are pH=7, 1 mmol l⁻¹ of ambient propionate, acetate and HCO₃⁻ and varying ambient H₂ pressures as shown on the x axis.