Probing the fate of structurally distinct Siderophores with reactive soil components

Siderophores, iron (Fe) chelating agents produced by fungi, bacteria, and grassy plants, play critical roles in the acquisition of Fe and other trace metals in terrestrial systems. Siderophores are essential to proper plant nutrition as well as the maintenance of soil quality and the suppression of plant diseases. The ability of siderophores to solubilize metals from minerals and the details of cellular uptake systems have been well-explored. However, limited studies have investigated mineral surface disruption of siderophore-promoted nutrient uptake processes, or the variable fate of structurally distinct siderophores and their metal complexes. Here, we examine the bacterial trishydroxamate siderophore desferrioxamine B (DFOB), the bacterial triscatecholamide siderophore protochelin, and the synthetic carboxylate phytosiderophore analog proline-2’-deoxymugeneic acid (PDMA), with soil aluminosilicates and metal (oxyhydr)oxides, including montmorillonite, kaolinite, goethite, ferrihydrit..., Sorption Isotherms (Figures 2-7). Sorption experiments were performed with apo-siderophores, and with Fe(III)- and Ga(III)-siderophore complexes. DFOB, PDMA, and protochelin isotherms were conducted with a solid to solution ratio of 2 g/L, 10 mM 2-(N-morpholino)ethanesulfonic acid (MES) buffer, and 0.02 M KCl background electrolyte, at pH 6. Initial concentrations included 0, 10, 50, 100, 150, 200, 250, 300, 400, and 500 µM siderophore or siderophore complex. Sorption (q) was calculated as amount lost from solution per gram solid, and equilibrium concentration refers to ÂµM siderophore remaining in solution.  X-ray absorption spectroscopy (Figures 8-10). Gallium K-edge extended X-ray absorption fine structure (EXAFS) spectra were collected at room temperature at Stanford Synchrotron Radiation Lightsource (SSRL) or the Advanced Photon Source. Spectra were collected for most Ga(III)-siderophore sorbed to mineral surfaces, free Ga sorbed to mineral surfaces, and aqueous Ga(III)-PD..., # Probing the fate of structurally distinct Siderophores with reactive soil components Dataset DOI: [10.5061/dryad.4b8gthtsq](https://doi.org/10.5061/dryad.4b8gthtsq) ## Description of the data and file structure ### File: Evers_2025_GCA_Data.zip #### Figures 2-7 Figure 2-7 contain adsorption isotherm data for the siderophores/Fe-siderophore complexes of DFOB, PDMA, or protochelin, onto the minerals, montmorillonite, kaolinite, goethite, ferrihydrite, and birnessite where: * measured C (micromolar siderophore)= equilibrium concentration of siderophore/Fe-siderophore in the supernatant * measured S (micromolar siderophore/g soil)= amount of siderophore/Fe-siderophore adsorbed to the mineral * modeled S (micromolar siderophore/ g soil)= Langmuir/freundlich isotherm fits of the data Example for Figures 2-7: For Figure 4, the figure is composed of 4 individual isotherms. Figure 4 contains isotherm data for Fe-PDMA birnessite, Fe-PDMA ferrihydrite, Fe-PDMA montmorillonite, and Fe-PDM..., ,