Selenate reduction by a Pseudomonas species: a new mode of anaerobic respiration

Abstract

The high levels of selenium (selenate, selenite) in agricultural drainage water in the San Joaquin Valley of California, which have led to environmental problems, might be lowered if the selenate/selenite could be reduced to elemental insoluble selenium. Two organisms have been newly isolated which do this in anaerobic coculture. One, a strictly anaerobic, Gram-positive rod, reduces selenite to elemental selenium. The other, a Pseudomonas species, was shown to respire selenate to selenite. Cells grown anaerobically in Minimal Medium on acetate plus selenate oxidized 14C-acetate to 14CO2 with concomitant reduction of selenate to selenite and small amounts of elemental selenium.

Chrysiogenes arsenatis gen. nov., sp. nov., a New Arsenate-Respiring Bacterium Isolated from Gold Mine Wastewater

“…The anoxic minimal medium described previously (14) was used, except that the sulfate concentration was 0.03 mg/liter. In enrichment cultures and when cultures were purified in agar medium (Oxoid purified agar, 1.5%) a reducing agent (0.03% cysteine) was present, and the concentration of arsenate and acetate was 10 mM.…”

“…When substrates used for growth were tested, the medium contained an electron acceptor (5 mM) plus an electron donor (5 mM); cysteine-HCl was not present in the medium. The standard anaerobic culture technique of Hungate was used for all of these experiments (14). All incubations were done at 28°C.…”

“…The enrichment was subcultured twice. A very motile, small, curved rod, designated BAL-lT, was isolated from the third enrichment subculture, using the same anaerobic medium containing 1.5% Oxoid purified agar in Hungate roll tubes (14). This organism has been deposited with the American Type Culture Collection as strain ATCC 700172.…”

Hydrological and geochemical investigations of selenium behavior at Kesterson Reservoir

“…Organo-selenium species include seleno-amino acids and volatile methylated Se compounds (Reamer and Zoller, 1980;Zieve and Peterson, 1981 ;Doran, 1982;Thompson-Eagle and Frankenberger, 1989). The essential role of microorganisms in catalyzing most Se transformations of environmental importance is now well-recognized (Doran, 1982;Zehr and Oremland, 1987;Jacobs, 1989;Macy et al, 1989;Oremland et al, 1989Oremland et al, , 1990Lortie et al, 1992;Frankenberger and Benson, 1994). Knowledge of Se speciation and partitioning within various environmental compartments is also important in evaluation of potential risks arising from deficiency or toxicity (Ohlendorf, 1989;Luoma et al, 1992).…”

Technical considerations for the implementation of subsurface microbial barriers for restoration of groundwater at UMTRA sites

“…During microbial reduction, soluble oxidized selenium (SeO42-or SeO32-) is reduced to insoluble elemental selenium (Se"). Microorganisms that can mediate the selenium reduction reaction include Wolinella succinogenes, Desulfovibrio desulfuricans and Pseudonomas bacteria (Macy et al, 1989;Tomei et al, 1992;Tomei et al, 1995). The chemistry of selenium is closely related to sulfur because of the similarity of thQr electron structure which is demonstrated by the fact that they are in the same column in the periodic chart.…”