title: Curium(III) complexation with pyoverdins secreted by a groundwater strain of Pseudomonas fluorescens.
abstract: Pyoverdins, bacterial siderophores produced by ubiquitous fluorescent Pseudomonas species, have great potential to bind and thus transport actinides in the environment. Therefore, the influence of pyoverdins secreted by microbes on the migration processes of actinides must be taken into account in strategies for the risk assessment of potential nuclear waste disposal sites. The unknown interaction between curium(III) and the pyoverdins released by Pseudomonas fluorescens (CCUG 32456) isolated from the granitic rock aquifers at the Aspö Hard Rock Laboratory (Aspö HRL), Sweden, is the subject of this paper. The interaction between soluble species of curium(III) and pyoverdins was studied at trace curium(III) concentrations (3 x 10(-7)M) using time-resolved laser-induced fluorescence spectroscopy (TRLFS). Three Cm(3+)-P. fluorescens (CCUG 32456) pyoverdin species, M(p)H(q)L(r), could be identified from the fluorescence emission spectra, CmH(2)L(+), CmHL, and CmL(-), having peak maxima at 601, 607, and 611 nm, respectively. The large formation constants, log beta(121 )= 32.50 +/- 0.06, log beta(111) = 27.40 +/- 0.11, and log beta(101) = 19.30 +/- 0.17, compared to those of other chelating agents illustrate the unique complexation properties of pyoverdin-type siderophores. An indirect excitation mechanism for the curium(III) fluorescence was observed in the presence of the pyoverdin molecules.
authors.affiliation: Institute of Radiochemistry, Forschungszentrum Dresden-Rossendorf, Dresden, Germany. h.moll@fzd.de
authors.forename: Henry
authors.initials: H
authors.lastname: Moll
authors.forename: Anna
authors.initials: A
authors.lastname: Johnsson
authors.forename: Mathias
authors.initials: M
authors.lastname: Schäfer
authors.forename: Karsten
authors.initials: K
authors.lastname: Pedersen
authors.forename: Herbert
authors.initials: H
authors.lastname: Budzikiewicz
authors.forename: Gert
authors.initials: G
authors.lastname: Bernhard
mesh_terms: D008671:Actinoid Series Elements / Q000737:chemistry / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D003476:Curium / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D015394:Molecular Structure; D009842:Oligopeptides / Q000737:chemistry / Q000378:metabolism*; D011551:Pseudomonas fluorescens / Q000378:metabolism*; D011850:Radioactive Waste; D017262:Siderophores / Q000737:chemistry / Q000378:metabolism*; D014873:Water Pollutants / Q000737:chemistry / Q000378:metabolism
chemical_list: D008671:Actinoid Series Elements; D001426:Bacterial Proteins; D009842:Oligopeptides; D011850:Radioactive Waste; D017262:Siderophores; D014873:Water Pollutants; C042453:pyoverdin; D003476:Curium