Lipid and wall amino acid composition in the classification and identification of Arachnia propionica

Two strains of Arachnia propionica and two Arachnia-like isolates were degraded by alkaline methanolysis and the non-hydroxylated fatty acid esters released were examined by thin-layer and gas chromatography. The fatty acid profiles obtained were both qualitatively and quantitatively similar and were comprised of iso-, anteiso- and straight chain saturated fatty acids with 13-methyltetradecanoic acid (i-15) and 12-methyltetradecanoic acid (ai-15) as major components. One of the Arachnia-like strains (HIK 288) had, in addition to i-15 and ai-15, major amounts of pentadecanoic acid (15:0). All of the strains gave characteristic polar lipid patterns consisting of diphosphatidylglycerol, phosphatidylglycerol and two incompletely characterised glycolipids. Analyses of wall amino acid preparations by gas and thin-layer chromatography showed that Arachnia propionica strains contain major amounts of alanine, glycine, glutamic acid and LL-diaminopimelic acid. The chemical data support the integrity of Arachnia propionica and provide a valuable means of differentiating it from morphologically and physiologically similar strains of Actinomyces israelii.