The mechanism of propionic acid formation by Veillonella gazogenes.

The evidence for this scheme is : (a ) Washed suspensions of the organism grown on lactate attack, under anaerobic conditions, pyruvate, oxalacetate, L-malate, fumarate and succinate, but not D-tartrate. (b) Organisms grown on D-tartrate attack it and all the substances listed in (a ) except lactate. ( c ) Succinic acid is quantitatively decarboxylated to propionic acid and carbon dioxide. (d ) The amount of propionic acid produced from lactate is influenced by the CO, concentration in the medium. ( e ) CO, is fixed in the carboxyl group of propionic acid during fermentation of lactate.