Isolation of Mycobactins from Various Mycobacteria

Mycobactin S has been isolated from Mycobacterium smegmati8 and from Mycobacterium sp. Olitzky & Gershon, strain 2, and mycobactin H from M. thermore8i8tible; all three organisms were grown on synthetic media of low iron content. These two mycobactins are mixtures of compounds having the same nucleus but differing in their fatty side chains. The nucleus of mycobactin S has a chemical structure identical with that ofmycobactin T but differs in the optical configuration at the fl-carbon atom ofthehydroxy acid fragment; the configuration inmycobactin S isS whereas that in mycobactin T is R (the previous assignment of this configuration was incorrect). The cobactin fragment of mycobactin H is identical with that of mycobactin S, but the mycobactic acid moiety differs in having methyl groups at position 6 in the benzene ring and at position 5 in the oxazoline ring. The configurations of all the asymmetric centres have been established for both mycobactins. Improved and simplified methods for the extraction and purification of mycobactins are described.