Isolation of a Bacterium, Producing Propionic Acid, from the Rumen of Sheep

SUMMARY: A strictly anaerobic microcoecus which produces acetic acid, propionie acid, carbon dioxide, and hydrogen by fermentation of lactate was isolated from the rumen of sheep. It failed to ferment sugars and was identified as Veillonella gazogenes. Its significance in ruminant digestion is uncertain, but a characteristic reaction of this organism, the decarboxylation of succinie acid to yield propionic acid and carbon dioxide, appears to be important in the rumen. This reaction was studied by the Warburg technique with washed suspensions of rumen bacteria.