Abstract
The ability of Pseudomonas to grow and to produce siderophores is dependent on the iron content and the type of carbon sources in the medium. Under conditions of low-iron concentration the Pseudomonas isolates studied produced yellow-green fluorescent iron-binding peptide siderophores and the biosynthesis of this siderophores was affected by several different environmental parameters. Four basal media, supplemented with different concentration of iron, were employed to study the effect of iron and different organic carbon sources on siderophore production in Pseudomonas fluorescens . The highest siderophores concentration was obtained in succinate medium. Ferric iron increased the growth yield and completely repressed siderophores production above 200 μg/l, but had a positive effect below 160μg/l. Penicillin and lead elicited the production of siderophores in the presence of excess iron. Pre-treatment of the standard succinate medium with a,a-dipyridyl and 8-hydroxyquinoline to reduce the concentration of iron diminished both the growth yield and siderophore production, but a,a-dipyridyl increased significantly the amount of siderophores produced in the presence of 0.20 mg/l of the chelating ion. African Journal of Biotechnology Vol. 4 (7), pp. 697-702, 2005
Highlights
Under aerated conditions at neutral to alkaline pH, inorganic iron is extremely insoluble and its concentration is less than optimal for bacterial growth (Lindsay and Schwab, 1982; Schwyn and Neilands, 1986)
We studied the influences of heavy metals and antibiotics on siderophore production
The strain was grown in succinate medium without adding iron and in the presence of α,α-dipyridyl (01, 0.15, 0.20, 0.25, 0.30, 0.35, and 0.40 mg/l) and 8-hydroxyquinoline (0.10, 0.20, 0.40, 0.60, 0.80, 1 mg/l)
Summary
Under aerated conditions at neutral to alkaline pH, inorganic iron is extremely insoluble and its concentration is less than optimal for bacterial growth (Lindsay and Schwab, 1982; Schwyn and Neilands, 1986). We have investigated the specific stimuli for siderophores production in local strains of P. fluorescens under different Fe (III) concentrations in the presence of various carbon sources. We studied the influences of heavy metals (lead, mercury and cadmium) and antibiotics (penicillin and streptomycin) on siderophore production.
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