Nicotinic acid metabolism. II. The isolation and characterization of intermediates in the fermentation of nicotinic acid.

6-Hydroxynicotinic acid was demonstrated to be the first intermediate in the degradation of nicotinic acid by a clostridium. In the presence of pyruvate, other intermediates accumulated; two of these were identified, one as 1,4,5,6tetrahydro-6-oxonicotinic acid, and the other as a!-methyleneglutaric acid. The pathways for nicotinic acid degradation may be considered as involving successive oxidative and reductive steps to 1,4,5,6-tetrahydro-6-oxonicotinic acid, then through some unidentified steps to a-methyleneglutaric acid, which is subsequently converted to propionic and acetic acids and carbon dioxide. Pyruvate and lactate were shown not to be obligatory intermediates in the production of propionate. This microorganism has a high content of Blz coenzyme, but its function in nicotinic acid fermentation is not yet understood.