Photodissolution of lepidocrocite (γ-FeOOH) in the presence of desferrioxamine B and aerobactin

Evidence for ligand hydrolysis and Fe(III) reduction in the dissolution of goethite by desferrioxamine-B

“…However, they also noted that it is difficult to deduce the number of types of DFOB-lepidocrocite surface complexes or the number of Fe(III) centers involved in an individual surface complex based solely on infrared spectroscopic results. Borer et al reported no evidence of DFOB hydrolysis or Fe(III) reduction in lepidocrocite suspensions in the dark between pH 3 and 8 (Borer et al, 2009b).…”

“…These include organic ligands called siderophores that have high affinity and specificity for Fe(III) and therefore can solubilize iron from minerals. The dissolution of Fe(III) bearing minerals in the presence of siderophores has been the subject of numerous recent studies (e.g., Reichard et al, 2005Reichard et al, , 2007Wolff-Boenisch and Traina, 2007;Haack et al, 2008;Borer et al, 2009b). These multidentate ligands often contain several a-hydroxycarboxylate, catecholate, and/or hydroxamate moities that chelate to metals (Kiss and Farkas, 1998;Hersman et al, 2000;Kraemer, 2004;Dhungana and Crumbliss, 2005;Sandy and Butler, 2009 The focus of this study is the reaction of a trihydroxamate siderophore, desferrioxamine-B (DFOB), with the Fe(III) bearing soil mineral, goethite (a-FeOOH), in the absence of visible light.…”

“…In 2002, Cocozza et al (2002) used the temperature dependence of goethite dissolution at pH 6.5 in the presence of DFOB and its noncharged acetyl derivative DFOD1 to suggest that DFOB adsorbs onto the goethite surface via only one hydroxamate group. Most recently, Borer et al (2009b) reported that inner-sphere coordination of DFOB at the lepidocrocite (c-FeOOH) surface dominates over pH range 4.0-8.2. Based on an infrared spectroscopic study, they suggested that DFOB is coordinated to surface Fe(III) sites of lepidocrocite via two or three hydroxamic groups (Borer et al, 2009a).…”

“…Several recent studies have also focused on the dissolution of Fe(III) bearing minerals in the presence of DFOB under visible light (Borer et al, 2005(Borer et al, , 2009b. In 2005, Borer et al showed that the presence of DFOB at pH 6 accelerates the photoreductive dissolution of lepidocrocite but not goethite.…”

The fate of siderophores: antagonistic environmental interactions in exudate-mediated micronutrient uptake

“…However, at the surface of iron minerals (specifically lepidocrocite, c-FeOOH), it has been demonstrated that both hydroxamate and a-hydroxycarboxylate siderophores may promote reductive dissolution when irradiated with ultraviolet light. This observation suggests that heterogeneous photochemical reactivity may occur more broadly than comparable reactions of dissolved siderophores and siderophore complexes (Borer et al 2009). Interestingly, the photochemical degradation of siderophores not only enhances uptake by bacteria but also by non-siderophore producing algae that tend to exist in association with bacteria (Amin et al 2009).…”