On the calculation of the free energy change accompanying the growth of escherichia coli K‐12 on succinic acid

Determinations of the Δ G 0 ′ accompanying the growth of Escherichia coli K‐12 on succinic acid are made using 2 different methods. The Δ G 0 ′ accompanying catabolism could be calculated directly because the thermodynamic properties of the reactants and products are known. The Δ G ′accompanying anabolism could not be calculated directly because the Δ G f value for a unit mass of cells was not known. A description is given of a deduction that the Δ G ′ accompanying anabolism is zero, or nearly so. This is followed by a description of 2 methods, whereby the free energy of formation of a unit quantity of cellular substance can be calculated. The 2 values obtained by these methods are used to calculate the free‐energy change accompanying anabolism, the resultant values being 1.72 and ‐11.68 kJ, respectively, with an average of −4.98 kJ (−1.19 kcal). This value is sufficiently close to zero that it can be considered to be so, indicating that the Δ G ′ accompanying metabolism is that of catabolism alone.