Growth kinetics of Acetobacterium sp. on methanol-formate in continuous culture.

The fermentative metabolism of Acetobacterium sp. grown on methanol-formate in continuous culture is described. The reaction stoichiometry of methanol-formate, including cells, were as follows: CH3OH + 1.13HCOOH --> 0.87CH3COOH + 0.47 cell C. Formate enhanced growth yields by approximately 60% compared with methanol-CO2-grown cultures. Comparison of yields on methanol-formate allowed calculation of an energy yield of 1.3 mol ATP per mol acetate formed during homoacetate fermentation. The magnitudes of YEG,the theoretical maximum yield of YE, and m, the maintenance coefficient, were determined by growing the organism in methanol-formate and resulted in 16.5 g cell (mol methanol catabolized)-1 and 0.674 mmol methanol catabolized (g cell)-1 h-1, respectively. It is concluded that formate might replace CO2 as a source of carboxyl donor.