Isolation and Characterization of an Fe(III)-Chelating Compound Produced by Pseudomonas syringae

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Abstract
The phytopathogenic bacterium Pseudomonas syringae produces a fluorescent pigment when it is grown in iron-deficient media. This pigment forms a very stable Fe(III) complex that was purified in this form by using a novel procedure based on ultrafiltration and column chromatography. The Fe(III) complex has a molecular weight of 1,100 and contains 1 mol of Fe(III). The pigment is composed of an amino acid moiety with three threonines, three serines, one lysine, δ- N -hydroxyornithine, and a quinoline-type fluorescent chromophore. These features and its stability constant (in the range of 10 32 ) suggest that the fluorescent pigment of P. syringae is related to the siderophores produced by another Pseudomonas species.