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.