Isolation, identification, and structural analysis of the mycobactins of Mycobacterium avium, Mycobacterium intracellulare, Mycobacterium scrofulaceum, and Mycobacterium paratuberculosis

Abstract

Methods were devised to purify the cell-associated, iron-binding compounds known as mycobactins from the closely related species Mycobacterum avium, Mycobacterium intraceUulare, and Mycobacterium scrofulaceum (i.e., the MAIS complex of organisms). The mycobactins from these three species showed a structure that is common to the mycobactins from all the mycobacteria examined to date. However, these mycobactins were unique in that they had more than one alkyl chain. The M. scrofulaceum mycobactins differed from other MAIS mycobactins by a shift in the position of the double bond in the Rl alkyl chain. Traces of other mycobactin types were observed in ethanol extracts of the three species, and examination of the chromatographic properties of these mycobactins showed that each species produced five mycobactin types. Each mycobactin could be subdivided further by the lengthi of its Rl alkyl chain. No differences in the production of these novel mycobactins were observed among species. Mycobactins from three strains of Mycobactenium paratuberculosis and two wood pigeon strains of Mycobacterium avium which had lost their original growth requirements for mycobactin after repeated subculturing in laboratory growth media were examined by thin-layer chromatography and high-pressure liquid chromatography. Each organism produced a mycobactin with similar chromatographic properties to thope synthesized by MAIS organisms. M. paratuberculosis NADC 18 produced at least two components in our laboratory, and nuclear magnetic resonance analysis of the major component showed this mycobactdli to be identical to that produced by M. intraceUlure M12. However, a samn4le of mycobactin J isolated by Merkal and McCullougb (Curr. Microbiol. 7:333-335, 1982) from M. paratuberculosis NADC 18 was different from our isolates and appeared to correspond to a minor mycobactin component we had seen by thin-layer chromatography. No reason for this difference could be evinced. Our findings indicate that there is a close taxonomic relationship between M. paratuberculosis and the MAIS complex.

DNA polymorphism in Mycobacterium paratuberculosis, "wood pigeon mycobacteria," and related mycobacteria analyzed by field inversion gel electrophoresis

“…Assignment of a mycobactin-dependent strain to a specific taxon depends on the source of isolation and associated pathogenicity. Other criteria such as microbiological and biochemical tests, fatty acid composition, peptidoglycolipid content, and immunodiffusion analysis have not established a reliable correlation between phenotype and pathogenicity (3,4,10,18,24,26).…”

Mycobactin analysis as an aid for the identification of Mycobacterium fortuitum and Mycobacterium chelonae subspecies

“…In 1970, Snow and White suggested the role of mycobactins as chemotaxonomic markers for identification of mycobacteria to the species level as different mycobactin structures were determined on the basis of the species examined (35). Mycobactin analysis of diverse species of mycobacteria and related genera has been performed mainly by Ratledge and collaborators (2,3,(11)(12)(13)(14)30). However, the method has not been widely applied for identification purposes, owing to constraining conditions of cell cultivation compatible with mycobactin production.…”

Paratuberculosis.

“…The absence of mycobactins from most strains of M. paratuberculosis and some M. avium isolates is intriguing. These strains multiply freely in parasitized hosts, while requiring an exogenous supplement of mycobactin for in vitro proliferation (5,6,145). Mycobactin dependence is no longer considered pathognomonic for identification of M. paratuberculosis since mycobactin-dependent wood pigeon mycobacteria and M. avium strains have been identified (128,202).…”