| Primary Source |
[21] Amend, J.P. and McCollom, T.M. (2009) Energetics of biomolecule synthesis on early Earth. In Chemical Evolution II: From the Origins of Life to Modern Society (Zaikowski, L. et al., eds), pp. 63–94, American Chemical Society [78] McCollom, T.M. and Amend, J.P. (2005) A thermodynamic assessment of energy requirements for biomass synthesis by chemolithoautotrophic microorganisms in oxic and anoxic environments. Geobiology 3, 135–144 DOI: 10.1111/j.1472-4669.2005.00045.x link |
| Comments |
P.19 2nd paragraph:"Importantly, Amend and McCollom [primary source 21] examined the thermodynamics for the synthesis of cell mass from H2, CO2, and NH3 under hydrothermal vent conditions of exactly the type that [investigators] have in mind here: an alkaline hydrothermal vent with H2-rich effluent interfacing with CO2-rich ocean water. They found that the synthesis of cell mass, corresponding to the same general composition as [investigators] outlined in Table 1 [BNID 112451], is endergonic at 25 °C but exergonic at 50 °C, and still exergonic, but less so, at higher temperatures. This is summarized in Table 2, the values in which were extracted with kind permission from Amend and McCollom [primary source 21]. The reader might think, at first sight, that this conflicts with the observation that the acetate-oxidizing core bioenergetic reaction of T. phaeum shifts from being exergonic under standard physiological conditions (25 °C and high H2 activity) to becoming exergonic enough for ATP synthesis at low H2 partial pressures and 55 °C [refs 73, 74]. Yet recall that the calculation for T. phaeum is for the equilibrium between H2, CO2, and acetate, which can be harnessed for the synthesis of ATP to drive physiology forward, whereas the calculations of Amend and McCollom [primary source 21] are for the synthesis of cell mass as an end product (Table 2)." See notes beneath table |