Characterization of siderophores produced by the genus Glutamicibacter sp.

Siderophores are low molecular weight compounds synthesized by bacteria, fungi, and plants under iron-deficient conditions (<1×10⁻⁶ M), often featuring functional groups like C=O, C=C, and C=N, which confer fluorescence, while hydroxyl groups (-OH) facilitate metal chelation, particularly with Fe³⁺ ions (Hider et al., 2010). In this research work, a siderophore belonging to a novel species of the genus Glutamicibacter sp. strain AlTeq-24-F2 was studied. The compound was purified using column chromatography and analyzed through a combination of spectroscopic and physicochemical techniques: FT-IR, UV-Vis, spectrofluorometry, ESI-MS, TGA, electrophoresis, and NMR spectroscopy (¹H, ¹³C, and HSQC). FT-IR spectra indicated the presence of OH, CH₂, CH₃, and C=O groups. Spectrofluorometry revealed strong fluorescence at 305 nm upon excitation at 230 nm, which diminished and shifted to 458 nm upon Fe³⁺ titration. UV/Vis spectroscopy showed bathochromic and hyperchromic shifts after metal complexation. TGA demonstrated high thermal stability. Zeta potential measurements confirmed a surface charge reversal (from negative to positive) after Fe³⁺ addition. NMR and ESI-MS data allowed the proposal of a tentative chemical structure based on fragment analysis and mass-to-charge correlations. The siderophore from Glutamicibacter sp. AlTeq-24-F2 exhibits promising physicochemical properties, especially its fluorescence and metal-binding capacity. These features suggest its potential for applications in metal sensing or bioremediation.