STUDIES ON OPTIMIZATION OF SIDEROPHORE PRODUCTION BY PSEUDOMONAS AERUGINOSA AZAR 11 ISOLATED FROM AQUATIC SOIL AND ITS ANTIBACTERIAL ACTIVITY

Author(s): Colombowala A and Aruna K*

Abstract: Background: Siderophores are low molecular weight iron-chelating molecules produced by micro-organisms to carry out multiple metabolic processes, where iron serves as a cofactor. Objectives: The objectives of the current study were to optimize and characterize siderophore production by bacterial isolate and determine its antibacterial activity. Method: In the present study, thirty-five bacterial cultures were isolated from five soil samples collected from aquatic environment and checked for siderophore production using CAS-agar assay method. Optimization of various physicochemical parameters was carried out for siderophore production by the most promising isolate which was identified by 16s rRNA gene sequencing analysis. Finally, the antibacterial activity of the siderophores was determined against the laboratory cultures as well as β-lactamase producing uropathogens. Results: Maximum siderophore production (59.18%) was obtained in king’s B medium (pH7) by Pseudomonas aeruginosa azar 11, in 72h at 37°C using a 5% inoculum size of 0.6O. D600nm under shaker conditions (120rpm). It was further observed that supplementation of 0.45% glycine (59.18%) in Kings B medium did not affect siderophore production, whereas 0.05% maltose (57.35%) slightly inhibited the same. However, other nutrient sources like ammonium nitrate (47.27%SU), proline (45.00%) and citric acid (33.89%SU) showed a considerable reduction in siderophore production. Among metal ions, cobalt sulfate (4.91%SU) significantly inhibited siderophore production. The cell-free extract of test culture also showed antibacterial activity against few of the test isolates. Conclusion: All these results collectively suggest appropriate industrial application of P. aeruginosa azar 11 for siderophore production after further optimization studies.

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