CELLULAR FATTY-ACID METHYL-ESTER PROFILES AS A TOOL IN THE DIFFERENTIATION OF MEMBERS OF THE GENUS MYCOBACTERIUM

The cellular fatty acid profiles of 84 strains belonging to 53 differe nt species of the genus Mycobacterium were determined by gas liquid ch romatography-mass spectrometry (GC-MS). Two main types and four subtyp es of fatty acid profiles were recognizable. The first main type is th e G type, nominally referring to M. gordonae, members of which lack tu berculostearic acid or other 10-methyl branched-chain fatty acids, but contain normal saturated and unsaturated fatty acids. This type is fu rther subdivided into the Galpha subtype that is characterized by 2-me thyl tetradecanoic acid (2-Me-C14:0) as the only 2-methyl branched fat ty acid. Strains belonging to the second main type, the T type, nomina lly referring to tuberculosis, contain tuberculostearic acid and other 10-methyl branched acids in addition to the normal saturated and unsa turated ones. This type has been further subdivided into three subtype s: the Talpha subtype that does not contain any 2-methyl branched fatt y acids; the Tbeta subtype that contains both 2-methyl tetradecanoic ( 2-Me-C14:0) and 2,4-dimethyl tetradecanoic (2,4-DMe-C14:0) acids as 2- methyl branched fatty acids; the Tgamma subtype which contains 2-methy l dodecanoic (2-Me-C12:0), 2,4-dimethyl dodecanoic (2,4-DMe-C12:0) and 2,4-dimethyl tetradecanoic (2,4-DMe-C14;0) acids as 2-methyl branched -chain acids. Fatty acid analysis showed a great homogeneity within th e genus and the profiles produced were not very helpful in distinguish ing between members of the genus Mycobacterium except for the identifi cation of M. gordonae, M. kansasii, and M. gastri.