← Back to Search
Changes In Molecular Species Composition Of Nocardomycolic Acids In Nocardia Rubra By The Growth Temperature
Published 1981 · Chemistry
Nocardomycolic acids from Nocardia rubra were fully separated and characterized by a combination of argentation thin-layer chromatography and gas chromatography — mass spectrometry (GCMS). The occurrence of 20 or more different molecular species of mycolic acids was demonstrated. GCMS analysis of each subclass of mycolic acids after separation on AgNO3 thin-layer chromatography revealed that in general the major species consisted of the even-carbon mycolic acids ranging from C38 to C52. However, the most abundant species differed by the subclasses; C44 being in saturated, C46 in monoenoic and C46 in dienoic mycolic acids, respectively. All these acids were shown to possess C12 or C14 alkyl branch at 2 position, while double bonds were located in longer straight chain alkyl unit. By using this method, distinctive changes in mycolic acid composition by growth temperature were observed. The ratios of saturated, monoenoic to dienoic mycolic acids in a mixture of certain carbon numbered mycolic acids varied greatly, according to the shift of growth temperature. The mass fragmentographic analysis, monitoring M-15 ions derived from the loss of methyl group from the molecular ions showed the lower temperature (15°C) grown cells contained more unsaturated (especially dienoic) mycolic acids, while the higher temperature (40°C) grown cells contained more saturated mycolic acids in both extractable and cell-wall bound lipids. These changes in mycolic acid composition occurred shortly after shifting up the growth temperature from 20°C to 43°C at a logarithmic stage of the bacterial growth.