Isolation and characterization of siderophores and envelope proteins from mycobacteria.

Mycobacteria produce two types of siderophores, the exochelins and the mycobactins under iron-starved conditions. Attempts were initiated to separate the exochelins and mycobactins isolated from four strains of mycobacteria grown under iron-deficient conditions by chromatographic procedures. The expression of iron-regulated envelope proteins were also studied. Autoradiography of exochelins labelled with 55Fe indicates that three M. tuberculosis strains produce similar kinds of exochelins but they are different from the exochelins produced by M. Smegmatis. The mycobactins from the three M.tuberculosis strains are identical but they are different from the mycobactins produced by M. Smegmatis. SDS-PAGE electrophoresis of membrane and cell-wall fractions from four strains of mycobacteria revealed a number of proteins under iron-deficient conditions.