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Figure 6. Comparison of energy needed for biomass synthesis on different carbon sources in mol ATP/C-mol biomass and in kJ/ C-mol biomass (1/Ygx). The numbers refer to the conventional biomass yield on ATP in gram biomass/mol ATP for different carbon sources (10).

and acetate is produced. The growth system contains biomass, NH4, H+, HCO3, H2O, methanol, and acetate as the seven compounds. The general macrochemical reaction equation for the production of 1 C-mol biomass can be written as follows:

+ cC2H3O2"

Clearly there are six unknown stoichiometric coefficients (a-f). However, using equation 3a we can calculate that (C = 1, y = 6 for methanol, maintenance has been neglected) 1/F2X = 200 + 326 + 172 = 698 kJ/C-molX. This means that we know that the Gibbs energy of reaction of the macrochemical reaction equation equals "698 kJ.

We can now write the conservation equations for C, H, O, N, electric charge, and the Gibbs energy balance (taking values of JG°1from Table 2):

C balance H balance O balance N balance charge balance f+ 2c + 1 + e = 0

Gibbs energy balance ("175.39) f + ("79.37)a + ("39.87)6 + ("369.41)c + ("237.18)d + ("67)1

Solving these six equations gives, for a to f, a = "0,2; b = 2.866; c = 8.898; d = 12.964; 