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

Determinations of the DeltaG(0)' accompanying the growth of Escherichia coli K-12 on succinic acid are made using 2 different methods. The DeltaG(0)' accompanying catabolism could be calculated directly because the thermodynamic properties of the reactants and products are known. The DeltaG'accompanying anabolism could not be calculated directly because the DeltaG(f) value for a unit mass of cells was not known. A description is given of a deduction that the DeltaG' 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 DeltaG' accompanying metabolism is that of catabolism alone.