Mycolic acid analysis in Nocardia species - The mycolic acid compositions of Nocardia asteroides, N. farcinica, and N-nova

Mycolic acids from twelve Nocardia species were analyzed for structure usin g capillary gas chromatography and mass spectrometry. This high-resolution procedure permitted good separation of the trimethylsilyl (TMS) ether deriv atives of mycolic acid methyl ester according to the total number of carbon and double bonds. The profiles of the mycolic acid molecular species were used as models to illustrate the difference in the structures of each speci es, even in the case of N. asteroides complex; N. asteroides, N. farcinica and N. nova. Although N. asteroides and N. farcinica had similar lengths of carbon skeleton, i.e., 51.9-53.7 was the average carbon number (Av.Nc.), t hey had different compositions of unsaturated acids. Mycolic acids from N. asteroides were composed of abundant saturated acids and less than 1% tetra enoic acids; mycolic acids from N. farcinica were composed of unsaturated a cids, which were composed of abundant dienoic acids, 2-12% of tetraenoic ac ids and a trace of pentaenoic acids. Zn contrast, Av.Nc, of mycolic acids f rom N. nova were 55.7-56.3, which were relatively longer than those from N. asteroides or N. farcinica. Regarding the characteristics of the structure of or-branch, major components were C16:0 and C18:0 for N. asteroides 2320 6(T), and C16:0 and C14:0 for N. farcinica 23157(T), respectively. The pres ence of monounsaturated cu-branch (C18:1 and C16:1) was characteristic of N . nova. (C) 1999 Elsevier Science B.V. All rights reserved.