title: A spectroscopic study on U(VI) biomineralization in cultivated Pseudomonas fluorescens biofilms isolated from granitic aquifers.
abstract: The interaction between the Pseudomonas fluorescens biofilm and U(VI) were studied using extended X-ray absorption fine structure spectroscopy (EXAFS), and time-resolved laser fluorescence spectroscopy (TRLFS). In EXAFS studies, the formation of a stable uranyl phosphate mineral, similar to autunite (Ca[UO2]2[PO4]2•2-6H2O) or meta-autunite (Ca[UO2]2[PO4]2•10-12H2O) was observed. This is the first time such a biomineralization process has been observed in P. fluorescens. Biomineralization occurs due to phosphate release from the cellular polyphosphate, likely as a cell's response to the added uranium. It differs significantly from the biosorption process occurring in the planktonic cells of the same strain. TRLFS studies of the uranium-contaminated nutrient medium identified aqueous Ca2UO2(CO3)3 and UO2(CO3)3 (4-) species, which in contrast to the biomineralization in the P. fluorescens biofilm, may contribute to the transport and migration of U(VI). The obtained results reveal that biofilms of P. fluorescens may play an important role in predicting the transport behavior of uranium in the environment. They will also contribute to the improvement of remediation methods in uranium-contaminated sites.
authors.affiliation: Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology, P.O. Box 51 01 19, 01314, Dresden, Germany, E.Krawczyk-Baersch@hzdr.de.
authors.forename: Evelyn
authors.initials: E
authors.lastname: Krawczyk-Bärsch
authors.forename: Laura
authors.initials: L
authors.lastname: Lütke
authors.forename: Henry
authors.initials: H
authors.lastname: Moll
authors.forename: Frank
authors.initials: F
authors.lastname: Bok
authors.forename: Robin
authors.initials: R
authors.lastname: Steudtner
authors.forename: André
authors.initials: A
authors.lastname: Rossberg
mesh_terms: D018441:Biofilms; D060587:Groundwater / Q000382:microbiology*; D008855:Microscopy, Electron, Scanning; D010710:Phosphates / Q000737:chemistry*; D011551:Pseudomonas fluorescens / Q000737:chemistry / Q000302:isolation & purification / Q000502:physiology*; D013050:Spectrometry, Fluorescence / Q000379:methods; D013816:Thermodynamics; D014501:Uranium / Q000737:chemistry; D017974:Uranium Compounds / Q000737:chemistry*; D056928:X-Ray Absorption Spectroscopy / Q000379:methods
chemical_list: D010710:Phosphates; D017974:Uranium Compounds; C075963:hydrogen uranyl phosphate; D014501:Uranium