Lipids in the classification of Nocardioides: reclassification of Arthrobacter simplex (Jensen) lochhead in the genus Nocardioides (Prauser) emend. O'Donnell et al. as Nocardioides simplex comb. nov.

Representative strains of Nocardioides, Arthrobacter simplex and Arthrobacter tumescens were degraded by acid methanolysis and the fatty acid esters released examined by thin-layer and gas chromatography. Branched-chain 14-methylpentadecanoic acid (iso-16) was the predominant component in all but one of the Nocardioides strains. Arthrobacter simplex also contained major amounts of this acid whereas A. tumescens had only minor amounts. All of the test strains possessed 15 and 17 carbon straight chain acids, tuberculostearic acid (10-methyloctadecanoic acid) and its 17 and 18-carbon homologues. The fatty acid profiles of Nocardioides strains lacked 13-methyltetradecanoic and heptadecanoic acids which were both present in Arthrobacter simplex and Arthrobacter tumescens. The profiles of these latter organisms were quantitatively different from each other. The polar lipids of the test strains all contained diphosphatidylglycerol and phosphatidylglycerol but only Arthrobacter tumescens contained phosphatidylinositol and three unidentified polar lipids. Nocardioides and Arthrobacter simplex strains all contained two very characteristic closely related polar lipids. All of the test strains contained tetrahydrogenated menaquinones with eight isoprene units as the major isoprenologue. The results of the present study support the integrity of the genus Nocardioides and provide a reliable way of distinguishing it from other actinomycetes, such as Streptomyces, which also have LL-diaminopimelic acid and glycine in the peptidoglycan. The lipid data, together with results from chemical, genetic and phage host range studies, provide sufficient grounds for the transfer of Arthrobacter simplex to Nocardioides as Nocardioides simplex comb. nov. An emended description of the genus Nocarioides is given.