. 1999 Mar;65(3):1152–1160. doi: 10.1128/aem.65.3.1152-1160.1999

TABLE 1.

Chemical reaction equations for the individual steps in mineralization of phthalate isomers and benzoate and the standard Gibbs free-energy changes during the conversions, corrected for a temperature of 37°C

Reaction no.	Reaction	Equation	ΔG⁰′, 37°C (kJ · reaction⁻¹)
1	Phthalate fermentation	C₈H₄O₄²⁻ + 8H₂O→3C₂H₃O₂⁻ + 3H⁺ + 3H₂ + 2HCO₃⁻	38.9^a
2	Benzoate fermentation	C₇H₅O₂⁻ + 7H₂O→3C₂H₃O₂⁻ + 3H⁺ + 3H₂ + HCO₃⁻	59.6
3	Hydrogenotrophic methanogenesis	0.75HCO₃⁻ + 0.75H⁺ + 3H₂→0.75CH₄ + 2.25H₂O	−98.4
4	Acetoclastic methanogenesis	3C₂H₃O₂⁻ + 3H⁺→3CH₄ + 3CO₂	−97.8
5	Mineralization of phthalate	C₈H₄O₄²⁻ + 6.5H₂O→3.75CH₄ + 2HCO₃⁻ + 2.25CO₂	−157.3
6	Mineralization of benzoate	C₇H₅O₂⁻ + 5.5H₂O→3.75CH₄ + HCO₃⁻ + 2.25CO₂	−136.6

The value represents the calculated ΔG⁰′ for isophthalate and terephthalate fermentation; the value for ortho-phthalate fermentation is estimated to be 34.9 kJ · reaction⁻¹. Applied ΔG_f⁰ values for ortho-phthalate, isophthalate, and terephthalate were −548.6, −552.6, and −552.7, respectively (5).