The Mechanism of Propionic Acid Formation by Veillonella gazogenes

Abstract

SUMMARY: The mechanism of propionic acid formation from lactate by Veillonella gazogenes is according to the scheme: CO2 lactate → pyruvate → cxaloacetate → malate → fimarate → succinate → propionate + CO2 The evidence for this scheme is: (a) Washed suspensions of the organism grown on lactate attack, under anaerobic conditions, pynivate, oxalacetate, l-malate. fumarate and suecinate, but d-tartrate. (b) Organisms grown on d-tartrate attack it and all the substances listed in (a) except lactate. (c) Succinie acid is quantitatively decarboxylated to propionic acid and carbon dioxide, (d) The amount of propionic acid produced from lactate is influenced by the CO2 concentration in the medium. (e) CO2 is fixed in the carboxyl group of propionic acid during fermentation of lactate.