Siderophore production by fluorescent pseudomonads colonizing roots of certain crop plants

Twelve fluorescent Pseudomonas isolates colonizing roots of four crop plants, chilli, cotton, groundnut and soybean, were examined for extracellular siderophore production in different media under iron deficient conditions. While all the organisms produced siderophores, they varied in the quantity of siderophores produced and in their preference to the medium. The siderophores were invariably hydroxamates (pyoverdine) of trihydroxamate type which formed bidentate ligands with Fe III ions.