Lipid and Wall Amino Acid Composition in the Classification of Rothia dentocariosa

Seven strains of Rothia dentocariosa were degraded by acid methanolysis and the non-hydroxylated fatty acid methyl esters released were examined by thin-layer and gas chromatography. The fatty acid profiles were composed of iso-, anteiso- and straight chain saturated fatty acids with 12-methyltetradecanoic (anteiso-C₁₅), 14-methylpentadecanoic (iso-C₁₆), 14-methylhexadecanoic (anteiso-C₁₇) and hexadecanoic acid (C₁₆) as major components. A small scale integrated procedure was used for the sequential extraction of isoprenoid quinones and polar lipids. The latter were examined by two-dimensional thin-layer chromatography and all of the test strains contained diphosphatidylglycerol, phosphatidylglycerol and two uncharacterised glycolipids. In all cases the major isoprenoid quinones were unsaturated menaquinones with seven isoprene units. Analyses of the cell wall amino acid composition using gas chromatography showed that the strains contained 2.5 to 5 moles of alanine and 1 mole each of glutamic acid and lysine. The chemical data support the integrity of Rothia dentocariosa and can be used to separate it from all other actinomycetes especially those which contain lysine in the wall peptidoglycan.