ABSTRACT
Siderophores are a group of natural compounds, produced by aerobic microorganisms to acquire and transport ferric iron under iron-stress conditions. The iron(III) chelating groups in siderophores are commonly of two types, hydroxamate and catecholate. Both of these groups are highly specific for ferric iron. Representative members of each of the three families of fungal siderophores have been crystallized and their complete structures and conformations have been determined by X-ray diffraction. Siderophores are produced inside the fungal cells under iron-deficient conditions, and then excreted out into the medium. The siderophores vary widely in their physical and chemical properties. This is why a single method of extraction may not be suitable for all of the siderophores produced by fungi, or even by a single fungus. The aqueous extract obtained from the chloroform-phenol extraction usually contains the ferric siderophores mixed with a large amount of colorless impurities.
