Effect of pyoverdine supply on cadmium and nickel complexation and phytoavailability in hydroponics
2015
Ferret, C. | Cornu, J. | Elhabiri, M. | Sterckeman, Thibault | Braud, A. | Jezequel, K. | Lollier, M. | Lebeau, T. | Schalk, I. | Geoffroy, V. | Service d'Hépato-Gastro-Entérologie et Nutrition [CHU Limoges] ; CHU Limoges | Laboratoire d'innovation moléculaire et applications (LIMA) ; Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut de Chimie - CNRS Chimie (INC-CNRS)-Centre National de la Recherche Scientifique (CNRS) | Laboratoire Sols et Environnement (LSE) ; Institut National de la Recherche Agronomique (INRA)-Université de Lorraine (UL) | Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG) ; Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST) ; Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS) | Equipe Dépollution Biologique des Sols ; Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))
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Show more [+] Less [-]English. Siderophores are chelators with a high selectivity for Fe(III) and a good affinity for divalent metals, including Cd(II) and Ni(II). Inoculation with siderophore-producing bacteria (SPB) has thus been proposed as an alternative to chelator supply in phytoremediation. Accurate assessments of the potential of this association require a dissection of the interaction of siderophores with metals at the soil–root interface. This study focuses on pyoverdine (Pvd), the main siderophore produced by Pseudomonas aeruginosa. We first assessed the ability of Pvd to coordinate Ni(II). The stability constant of Pvd–Ni(II) (log K L′Ni = 10.9) was found to be higher than that of Pvd–Cd(II) (log K L′Cd = 8.2). We then investigated the effect of a direct supply of Pvd on the mobilization, speciation, and phytoavailability of Cd and Ni in hydroponics. When supplied at a concentration of 50 μM, Pvd selectively promoted Ni mobilization from smectite. It decreased plant Ni and Cd contents and the free ionic fractions of these two metals, consistent with the free ion activity model. Pvd had a more pronounced effect for Ni than for Cd, as predicted from its coordination properties. Inoculation with P. aeruginosa had a similar effect on Ni phytoavailability to the direct supply of Pvd.
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