TRANSFORMATION OF SELENATE AND SELENITE TO ELEMENTAL SELENIUM BY DESULFOVIBRIO-DESULFURICANS

Desulfovibrio desulfuricans (DSM 1924) can be adapted to grow in the p resence of 10 mM selenate or 0.1 mM selenite. This growth occurred in media containing formate as the electron donor and either fumarate or sulfate as the electron acceptor. As determined by electron microscopy with energy-dispersive X-ray analysis, selenate and selenite were red uced to elemental selenium which accumulated inside the cells. Seleniu m granules resulting from selenite metabolism were cytoplasmic while g ranules of selenium resulting from selenate reduction appeared to be i n the periplasmic region. The accumulation of red elemental selenium i n the media following stationary phase resulted from cell lysis with t he liberation of selenium granules. Growth did not occur with either s elenate or selenite as the electron acceptor and C-13 nuclear magnetic resonance indicated that neither selenium oxyanion interfered with fu marate respiration. At 1 mu M selenate and 100 mu M selenite, reductio n by D. desulfuricans was 95% and 97%, respectively. The high level of total selenate and selenite reduced indicated the suitability of D. d esulfuricans for selenium detoxification.