High-performance liquid chromatography of α-keto acid production as a taxonomic tool for black-pigmented oral anaerobic rods

Abstract Black-pigmented oral anaerobic rods were incubated in a chemically defined medium containing amino acids. Metabolically produced α-keto acids were quantitatively profiled by high-performance liquid chromatography (HPLC). The tested bacteria were separated into two groups according to quantitative difference in production of the total α-keto acids. Higher production was associated with Porphyromonas species while lower production was associated with Prevotella species. In both genera, the relative degree of production of the characteristics α-keto acids, such as aromatic and branched-chain α-keto acids, was a chemotaxonomic index for classifying individual species. Interspecies-differentiation by the HPLC profiling agreed with the taxonomic revision which the black-pigmented anaerobic rods recently underwent, indicating that the HPLC characterization of α-keto acid production is useful for bacterial taxonomy.