Quantitative Comparison of the Mycolic and Fatty Acid Compositions of Mycobacterium leprae and Mycobacterium gordonae

Abstract

The mycolic and fatty acids of 3 samples each of M. leprae and M. gordonae were compared. Acids released by whole-organism alkaline hydrolysis were converted to 4-nitrobenzyl esters and mycolic acids were further derivatized to t-butyldimethylsilyl ethers. TLC of the derivatized long-chain extracts showed that all 3 M. leprae preparations contained so-called .alpha.-mycolates and ketomycolates but that the M. gordonae samples had a methoxymycolate in addition to the above the types. Silica gel normal-phase high-performance liquid chromatography of the total mycolic acid derivatives confirmed the lack of detectable amounts of methoxymycolates in M. leprae and reverse-phase chromatography of the individual mycolate types demonstrated the homogeneity of the chain lengths of the mycolic acids in each species. Non-hydroxylated fatty acid-4-nitrobenzyl esters were transformed to methyl esters and examined by gas chromatography. Tuberculostearic (10-methyloctadecanoic) acid was a major component of the lipids of all 3 M. leprae preparations but it was absent in 1 M. gordonae strain and a very minor component in the other representatives of this latter species. On the basis of fatty and mycolic acid compositions, therefore, a previously suggested close relationship between M. leprae and M. gordonae was not supported.