2D Image Quantification of Microbial Iron Chelators (Siderophores) Using Diffusive Equilibrium in Thin Films Method

• Published in: Analytical chemistry (Washington) Vol. 91; no. 2; pp. 1399 - 1407
• Main Authors: Le Houedec, Sandrine, Thibault de Chanvalon, Aubin, Mouret, Aurélia, Metzger, Edouard, Launeau, Patrick, Gaudin, Pierre, Lebeau, Thierry
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 15.01.2019
• Subjects: Bacteria; Chelating agents; Chelation; Chemistry; Cultivation; Deferoxamine; Environmental Sciences; Fungi; Grain cultivation; Iron; Iron and steel making; Ligands; Metals; Microorganisms; Pseudomonas fluorescens; Rhizosphere; Siderophores; Spatial distribution; Thin films; Wheat
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/acs.analchem.8b04021

Siderophores are natural metal chelating agents that strongly control the biogeochemical metal cycles such as Fe in the environment. This article describes a new methodology to detect and quantify at the micromolar concentration the spatial distribution at millimeter scale of siderophores within the root’s system. The “universal” CAS assay originally designed for bacterial siderophores detection and later designed for fungus was adapted here for diffusive equilibrium in thin film gel techniques (DET). The method was calibrated against the marketed desferrioxamine mesylate (DFOM) siderophore and applied with experiments performed with sunflower (Helianthus annuus) and wheat (Triticum aestivum) cultivated on free iron agar medium plates. We present here the first results with 2D images of the siderophores distribution in the vicinity of the root system of plants. With this technique we detected (i) the production of siderophores on bacteria inoculated (Pseudomonas fluorescens) environments and (ii) hotspots of natural iron binding ligands production up to 50 μM in the wheat rhizosphere. The lower detection limit in our experiment was 2.5 μmol/L. This new technique offers a unique opportunity to investigate the siderophore production in two dimensions in a wide range of applications from laboratory experiments to natural systems very likely using an in situ and nondestructive tool.