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PLoS ONE 3, 2 (2008) e1539
Heavy Metal Tolerance in Stenotrophomonas maltophilia.
Delphine Pages 1, Jerome Rose 2, Sandrine Conrod 3, Stephane Cuine 1, Patrick Carrier 4, Thierry Heulin 1, Wafa Achouak ( ) 1

Stenotrophomonas maltophilia is an aerobic, non-fermentative Gram-negative bacterium widespread in the environment. S. maltophilia Sm777 exhibits innate resistance to multiple antimicrobial agents. Furthermore, this bacterium tolerates high levels (0.1 to 50 mM) of various toxic metals, such as Cd, Pb, Co, Zn, Hg, Ag, selenite, tellurite and uranyl. S. maltophilia Sm777 was able to grow in the presence of 50 mM selenite and 25 mM tellurite and to reduce them to elemental selenium (Se(0)) and tellurium (Te(0)) respectively. Transmission electron microscopy and energy dispersive X-ray analysis showed cytoplasmic nanometer-sized electron-dense Se(0) granules and Te(0) crystals. Moreover, this bacterium can withstand up to 2 mM CdCl(2) and accumulate this metal up to 4% of its biomass. The analysis of soluble thiols in response to ten different metals showed eightfold increase of the intracellular pool of cysteine only in response to cadmium. Measurements by Cd K-edge EXAFS spectroscopy indicated the formation of Cd-S clusters in strain Sm777. Cysteine is likely to be involved in Cd tolerance and in CdS-clusters formation. Our data suggest that besides high tolerance to antibiotics by efflux mechanisms, S. maltophilia Sm777 has developed at least two different mechanisms to overcome metal toxicity, reduction of oxyanions to non-toxic elemental ions and detoxification of Cd into CdS.
1 :  Institut de Biologie Environnementale et Biotechnologie (IBEB)
2 :  Centre européen de recherche et d'enseignement de géosciences de l'environnement (CEREGE)
CNRS : UMR6635 – Institut de recherche pour le développement [IRD] – INSU – Université de Provence - Aix-Marseille I – Université Paul Cézanne - Aix-Marseille III
3 :  Université de Provence - Aix-Marseille 1
Université de Provence - Aix-Marseille I
4 :  Plastic Omnium Auto Exterior - Sigmatech
Plastic Omnium
Sciences du Vivant/Biologie végétale

Sciences du Vivant/Toxicologie
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