Uranium (VI) Complexation with Siderophores ...

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Shimaa S. Hussien1, Osman A. Desouky2, Mahmoud E.F. Abdel-Haliem3, Abdou ... a r Ene rgy Science a nd Engine ering Volume 3 I s sue 4, De cember 2013.

Inte rnational Journal of Nucle ar Ene rgy Science and Engine ering Volume 3 Issue 4, De cember 2013 doi: 10.14355/ijnese.2013.0304.03

www.ijne se .org

Uranium (VI) Complexation with Siderophores-pyoverdine Produced by Pseudomonas Fluorescens SHA 281 Shimaa S. Hussien1 , Osman A. Desouky2 , Mahmoud E.F. Abdel-Haliem 3 , Abdou A. El-Mougith4 Nuclear Materials Authority, P.O. Box 530 El-Maadi, Cairo, Egypt

1,2

Department of Botany, Faculty of Science, Zagazig University, Egypt

3,4

College of Science and Arts at Nayriya, Dammam University, Kingdom of Saudia Arabia

3

[email protected]

1

Abstract Fluore sce nt Pseudomonas species produce pyove rdine -type siderophores with a high pote ntial to dissolve ; bind and transport uranium in the e nvironment. Ide ntification of Pseudomonas fluorescens SHA 281 was confirme d by 16S rDNA se que ncing. The pyoverdine produce d by the tested strain was e xtracte d and purifie d using XAD-4 Ambe rlite re sin and its chemical structure was confirme d using NMR and CA-MS analyses. The ge l e lectrophoresis of pyoverdine appeare d low molecular we ight with one prote in band at ~12.5 kDa. The ge ne responsible for pyoverdine production was ide ntifie d using PCR technique . Unde r optimum conditions for comple xation, it was found that pyoverdine comple xe d with about 90.48 % and 86.41 % of U (VI) from monazite and (Th-U) conce ntrate, respectively. Keywords Uranium; Pyoverdines; Complexation; Pseudomonas Fluorescens

Abbreviations: Common amino acids, 3-letter code; OHAsp, _β hydroxy Asp; cOHOrn, cyclo-N5-hydroxyOrn(3-amino-1-hydroxy-piperidone-2); Chr, pyoverdine chromophore; Suca, succinamide residue; MS, mass spectrum or spectrometry; CA, collision activation; NMR, Nuclear magnetic resonance; kDa, killo dalton; SDS, sodium dodecyl sulfate; Pvd, pyoverdine and PVdS, siderophores-pyoverdine gene. Introduction Extensive knowledge of the interactions which occur between radionuclides and the biosphere is necessary in order to predict the possible migration of these elements. Pseudomonas fluorescens is one of the fluorescent pseudomonads that secrete pyoverdines for its essential requirement for iron (Meyer, 2000). Pyoverdine is a water soluble, yellow-greenish fluorescent siderophore involved in high affinity transport of iron into the cell due to presence of a

chromophore (Budzikiewicz, 1993). Structurally, it can be divided into three different parts: (a) a peptide chain composed of 6 to 12 mainly hydrophilic amino acids bound via their N-termini to the carboxyl group of the chromophore, (b) the chromophor(1S)-5-amino-2, 3-dihydro-8, 9-dihydroxy-1H-pyrimido[1,2-a] quinoline -1-carboxylic acid, and (c) an acyl chain attached to the NH2 group of the chromophore consisting of dicarboxylic acid residues. Succinate or its amide form depends on the growth conditions of the producer microorganism (Meyer, 2000). Siderophores are relatively low-molecular-mass (

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