Characterization of exochelins of the Mycobacterium bovis type strain and BCG substrains

Pathogenic mycobacteria must acquire iron in the host in order to multiply and cause disease. To do so, they release abundant quantities of siderophor es called exochelins, which have the capacity to scavenge iron from host ir on-binding proteins and deliver it to the mycobacteria. In this study, we h ave characterized the exochelins of Mycobacterium bovis, the causative agen t of bovine and occasionally of human tuberculosis, and the highly attenuat ed descendant of M. bovis, bacillus Calmette-Guerin (BCG), widely used as a vaccine against human tuberculosis. The M. bovis type strain, five substra ins of M. bovis BCG (Copenhagen, Glare, Japanese, Pasteur, and Tice), and t wo strains of virulent Mycobacterium tuberculosis all produce the same set of exochelins, although the relative amounts of individual exochelins may d iffer. Among these mycobacteria, the total amount of exochelins produced is greatest in M. tuberculosis, intermediate in M. bovis, and smallest in M. bovis BCG.