2-keto-L-gulonic acid (2-KLG) is a direct precursor (lactone) of L-ascorbic acid (vitamin C). 2-Keto-L-gulonic Acid is used in biological studies for the formation of sorbitol metabolism by Acetobacter melanogenus. Ketogulonigenium vulgare has long been used in industry to produce 2-keto-L-gulonic acid (2KGA).

2-pyridone-5-carboxylic acid (also known as 6-hydroxynicotinic acid) is formed from the nicotinic acid under the action of Pseudomonas aeruginosa and Serratia marcescens. The quantity of 6-hydroxynicotinic acid produced correlates well with the viable bacterial count. All others bacteria causing urinary infection, such as Escherichia coli, Klebsiella pneumonia, Enterobacter aerogenes, Enterococcus faecalis, Streptococcus gp B and Staphylococcus aureus do not metabolize nicotinic acid under similar conditions.