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Transformations of selenate and selenite by Stenotrophomonas maltophilia isolated from a seleniferous agricultural drainage pond sediment
Author(s) -
Dungan Robert S.,
Yates Scott R.,
Frankenberger William T.
Publication year - 2003
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1046/j.1462-2920.2003.00410.x
Subject(s) - stenotrophomonas maltophilia , selenium , selenate , biology , environmental chemistry , selenide , bacteria , sediment , stenotrophomonas , botany , chemistry , 16s ribosomal rna , organic chemistry , paleontology , genetics , pseudomonas aeruginosa
Summary A Gram‐negative bacterium, identified as Stenotrophomonas maltophilia by fatty acid analysis and 16S rRNA sequencing, was isolated from a seleniferous agricultural evaporation pond sediment collected in the Tulare Lake Drainage District, California. In cultures exposed to the atmosphere, the organism reduces selenate (SeO 4 2− ) and selenite (SeO 3 2− ) to red amorphous elemental selenium (Se°) only upon reaching stationary phase, when O 2 levels are less than 0.1 mg l –1 . In 48 h, S . maltophilia removed 81.2% and 99.8% of added SeO 4 2− and SeO 3 2− (initial concentration of 0.5 mM), respectively, from solution. Anaerobic growth experiments revealed that the organism was incapable of using SeO 4 2− , SeO 3 2− , SO 4 2− or NO 3 – as a terminal electron acceptor. Transmission electron microscopy of cultures spiked with either Se oxyanion were found to contain spherical extracellular deposits. Analysis of the deposits by energy‐dispersive X‐ray spectroscopy revealed that they consist of Se. Furthermore, S . maltophilia was active in producing volatile alkylselenides when in the presence of SeO 4 2− and SeO 3 2− . The volatile products were positively identified as dimethyl selenide (DMSe), dimethyl selenenyl sulphide (DMSeS) and dimethyl diselenide (DMDSe) by gas chromatography‐mass spectrometry. Our findings suggest that this bacterium may contribute to the biogeochemical cycling of Se in seleniferous evaporation pond sediments and waters. This organism may also be potentially useful in a bioremediation scheme designed to treat seleniferous agricultural wastewater.