ISOLATION AND CHARACTERIZATION OF CARBOXYMYCOBACTINS AS THE 2ND EXTRACELLULAR SIDEROPHORES IN MYCOBACTERIUM-SMEGMATIS

The structure of a chloroform-extractable siderophore from the superna tant of a nonpathogenic mycobacteria, Mycobacterium smegmatis, has bee n determined and it closely resembles the structure of mycobactin, the intracellular siderophore found in all mycobacteria. The difference i n structures is that the extracellular siderophore has a family of sho rt carboxylic chains attached to the mycobactin nucleus instead of a l ong alkyl chain and hence the name `carboxymycobactin' is proposed to distinguish it from mycobactin itself as well as from the major sidero phore that is produced - exochelin MS.