Selenium, Geomicrobiology, USGS Microbiology Research

Browse samples of USGS research about geomicrobiology and the selenium. For related links, see Related Links and References at the bottom of page.

Microbial Selenium Cycle in Nature

Growth of B. selenitireducens on selenite with its concomitant reduction to Se(0) and oxidation of lactate to acetate plus CO2 (left panel). Electron micrograph showing a cell with external accumulations of elemental selenium nanospheres on its surface (right panel). From Switzer Blum et al. (1998). Larger View

The selenium cycle in nature demonstrating the anaerobic reduction of selenate through selenite to elemental selenium and then to selenide. The arrows on the right side were drawn thicker to indicate that the reaction rates of dissimilatory reduction are orders of magnitude more rapid than bacterial oxidation. Adapted from Dowdle and Oremland (1998) and Herbel et al. (2003). Larger View

Naturally-occurring selenium in irrigated farm soils was found to be the cause of the mass death of wildlife in the former Kesterson Wildlife Refuge in the mid-1980s. As part of a broad research program on the biogeochemistry of this toxic element, an important discovery was reported in 1989 that documented the ability of anaerobic microorganisms to respire toxic oxyanions of selenium, namely selenate and selenite, and reduce them to insoluble elemental selenium as well as hydrogen selenide. These reactions effectively removed these toxicants from solution via a microbially mediated precipitation. Subsequent investigations found this phenomenon to be widespread in the environment, and that rates of “dissimilatory reduction” were rapid, especially when compared with re-oxidation. Several new species of anaerobic microorganisms were isolated and described that could grow by using either selenate or selenite as their respiratory electron acceptor for the oxidation of organic carbon substrates like lactate or acetate to carbon dioxide. For more information go to: Microbial Biogeochemistry of Aquatic Environments

View selected publications under Related Links and References.

For more information contact Ronald S. Oremland, Menlo Park Regional Office.

Sediment porewater profiles taken from an agicultural wastewater evaporation pond in the San Joaquin Valley of California. The selenium oxyanions are removed from solution at the top of the core by bacterial reduction to Se(0). From Oremland et al. (1989). Larger View

Microbial Selenium Cycle in Nature

Oremland, R.S. , J.T. Hollibaugh, A.S. Maest, T.S. Presser, L. Miller, and C. Culbertson. 1989. Selenate reduction to elemental selenium by anaerobic bacteria in sediments and culture: Biogeochemical significance of a novel, sulfate-independent respiration. Appl. Environ. Microbiol. 55: 2333-2343. (online abstract and full text)
Oremland, R.S., N.A. Steinberg, A.S. Maest, L.G. Miller, and J.T. Hollibaugh. 1990. Measurement of in situ rates of selenate removal by dissimilatory bacterial reduction in sediments. Env. Sci. Technol. 24: 1157-1164.
Steinberg, N.A. and R.S. Oremland. 1990. Dissimilatory selenate reduction potentials in a diversity of sediment types. Appl. Environ. Microbiol. 56: 3550-3557.
Oremland, R.S., J. Switzer Blum, C.W. Culbertson, P.T. Visscher, L.G. Miller, P. Dowdle, and F.E. Strohmaier. 1994. Isolation, growth and metabolism of an obligately anaerobic, selenate-respiring bacterium, strain SES-3. Appl. Environ. Microbiol. 60: 3011 - 3019.
Dowdle, P.R., and R.S. Oremland. 1998. Microbial oxidation of elemental selenium in soils and bacterial cultures. Environ. Sci. Technol. 32: 3749 – 3755.
Switzer Blum, J., A. Burns Bindi, J. Buzzelli, J.F. Stolz, and R.S. Oremland. 1998. Bacillus arsenicoselenatis sp. nov., and Bacillus selenitireducens sp. nov. : two haloalkaliphiles from Mono Lake, California which respire oxyanions of selenium and arsenic. Arch. Microbiol. 171: 19 – 30.
Stolz, J.F., D.J. Ellis, J. Switzer Blum, D. Ahmann, R.S. Oremland, and D.R. Lovley. 1999. Sulfurospirillum barnesii sp. nov., Sulfurospirillum arsenophilus sp. nov., and the Sulfurospirillum clade in the Epsilon Proteobacteria. Int. J. Systematic Bacteriol. 49: 1177 - 1180.
Stolz, J.F., and R.S. Oremland. 1999. Bacterial respiration of selenium and arsenic. FEMS Microbiology Reviews, 23: 615 - 627. (on-line abstract )
Oremland, R.S., J.S. Blum, A. Burns Bindi, P.R. Dowdle, M. Herbel, and J.F. Stolz. 1999. Simultaneous reduction of nitrate and selenate by cell suspensions of Se-respiring bacteria. Appl. Environ. Microbiol. 65: 4385 - 4392. (on-line abstract and full text)
Herbel, M.J., T.M. Johnson, R.S. Oremland, and T.D. Bullen. 2000. Fractionation of selenium isotopes during bacterial respiratory reduction of selenium oxyanions. Geochim. Cosmochim. Acta 64: 3701 – 3709. (on-line abstract)
Switzer Blum, J., J.F. Stolz, A. Oren, and R.S. Oremland. 2001. Selenihalanaerobacter shriftii gen. nov., sp. nov., a halophilic anaerobe from Dead Sea sediments that respires selenate. Arch. Microbiol. 175: 208 - 219. (on-line abstract)
Herbel, M.J., J.Switzer Blum, S. Borglin, and R.S. Oremland. 2003. Reduction of elemental selenium to selenide: Experiments with anoxic sediments and bacteria that respire Se-oxyanions. Geomicrobiol. J. 20: 587 - 602.
Stolz, J.F., P. Basu, J.M. Santini and R.S. Oremland. 2006. Arsenic and selenium in microbial metabolism. Ann. Rev. Microbiology 60: 107 – 130.