Aminochelin, a Catecholamine Siderophore Produced by Azotobacter vinelandii

A catecholamine siderophore, named aminochelin, produced by iron-limited Azotobacter vinelandii was purified and tentatively identified as 2,3-dihydroxybenzoylputrescine. This compound was first observed as an ethyl-acetate-insoluble catechol that accounted for 30 to 50% of the total catechol in iron-limited culture supernatant fluids. The purified compound was unstable at neutral to alkaline pH, bound Fe3+, Fe2+ and molybdate, and promoted 55Fe-uptake into iron-limited A. vinelandii. Aminochelin was induced and repressed coordinately with the other catechol siderophore azotochelin. The catechol siderophores were, however, less sensitive to repression by soluble iron than the yellow-green fluorescent peptide siderophore azotobactin.