Skip to main content
. 2000 Jul;66(7):2934–2942. doi: 10.1128/aem.66.7.2934-2942.2000

TABLE 1.

Reactions involved in the degradation of propionate and their standard Gibbs free-energy changes, corrected for a pH of 6.9 and a temperature of 37°Ca

Reaction Equationb ΔG0′ (kJ/reaction)
1. Propionate oxidation C3H5O2 (aq) + 2H2O (l) → C2H3O2 (aq) + CO2 (g) + 3H2 (g) +68.4
2. Hydrogenotrophic methanogenesis 4H2 (g) + CO2 (g) → CH4 (g) + 2H2O (l) −125.9
3. Syntrophic oxidation of propionate C3H5O2 (aq) + 1/2H2O (l) → C2H3O2 (aq) + 3/4(CH4 (g) + 1/4CO2 (g) −26.0
4. Sulfidogenic oxidation of propionate C3H5O2 (aq) + 3/4SO42− (aq) + 3/4H+ → C2H3O2 (aq) + CO2 (g) + 3/4HS− (aq) + H2O (l) −42.8
a

Temperature correction was made with the Gibbs-Helmholtz equation. The applied ΔHf0 for propionate was −460.2 kJ mol−1, which was calculated as described by Hanselmann (10). 

b

Abbreviations: aq, aqueous; l, liquid; g, gaseous.