Circumvention of the Mycobactin Requirement of Mycobacterium paratuberculosis

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Abstract
Morrison, Norman E. (Johns Hopkins University-Leonard Wood Memorial Leprosy Research Laboratory, Baltimore, Md.). Circumvention of the mycobactin requirement of Mycobacterium paratuberculosis . J. Bacteriol. 89: 762–767. 1965.—The mycobactin growth requirement of Mycobacterium paratuberculosis was circumvented on glucose-containing synthetic medium with an initial p H of 5.5. Mycobactin was required during the first transfer on the synthetic medium. Subsequent transfers have grown in the absence of mycobactin. The growth of mycobactin-“independent” strains of M. paratuberculosis on the synthetic medium was found to be stimulated by low concentrations of mycobactin. The circumvention of the mycobactin requirement appears to depend upon the properties of the medium and not upon having created conditions which promote endogenous mycobactin synthesis. Investigation of the glucose-containing synthetic medium showed that: (i) growth stimulatory compounds were formed during autoclaving, and (ii) compared with neutrality a p H of 5.5 gave markedly increased pellicle yields. It was suggested that the growth-stimulatory compounds formed during autoclaving may in part be responsible for the circumvention of the mycobactin requirement.