||G. T. Macfarlane and G. R. Gibson, Metabolic Activities of the Normal Colonic Flora, chapter 2 in Human Health: The Contribution of Microorganisms, Edited by S. A. W. Gibson, Springer-Verlag 1994 link , p.43 bottom paragraph
||Thauer RK, Jungermann K, Decker K (1977) Energy conservation in chemotrophic anaerobic bacteria. Bacteriol Rev 41: 100-180PubMed ID860983
||P.43 bottom paragraph: "The reduction of CO2 by H2 as carried out by acetogenic bacteria (AB) occurs as shown below: 4H2 + 2C02 > CH3COO- + H+ + 2H20 This reaction has a ΔG˚' of -95kJ per mol making it considerably less efficient energetically than either methanogenesis or dissimilatory sulphate reduction (primary source)."