Biochemical characteristics and fatty acid compositions of some armadillo-derived mycobacteria and their relation to Mycobacterium gordonae.

The long-chain components of 75 strains of mycobacteria, cultivated from Mycobacterium leprae-infected or non-infected armadillos, and of eight clinical and 15 environmental isolates of M. gordonae, were compared. Four major groups could be distinguished based on the presence of 10-methyloctadecanoic (tuberculostearic) and 2-methyl 3-hydroxyeicosanoic acids and secondary alcohols (2-octadecanol and 2-eicosanol). Some heterogeneity was found in strains assigned to M. gordonae: the characteristic absence of tuberculostearic acid and secondary alcohols and the presence of the branched C14 and the hydroxylated C20 acids were seen in only 34 of the 49 strains studied. Three strains were identified as M. malmoense, one as M. kansasii, ten as belonging to the M. avium-M. intracellulare-M. scrofulaceum complex and eight as belonging to new groups of armadillo-derived mycobacteria (ADM 1, ADM 2 and ADM 3) by conventional bacteriological tests and fatty acid compositions, though M. malmoense was heterogeneous in its fatty acids composition. Four strains, identified as M. avium by conventional tests, differed from this species by their fatty acid compositions. Thirteen strains showed some similarity to M. simiae and ten strains differed from all other known mycobacteria.