Reduction of selenate and selenite to elemental selenium by Wolinella succinogenes

Abstract

Cultures of Wolinella succinogenes were adapted to grow in the presence of 1 mM [Formula: see text] or 10 mM [Formula: see text]. Both selenium salts were reduced to red, amorphous, elemental selenium but only after the culture reached the stationary growth phase. Bacterial cells taken from a culture actively reducing selenium were examined by transmission electron microscopy and were found to have large, electron-dense granules in the cytoplasm. These granules were verified by energy-dispersive X-ray spectroscopy to consist of selenium. Wolinella succinogenes was unable to grow with [Formula: see text] or [Formula: see text] as the final electron acceptor. Key words: Wolinella, selenium, cytology, selenate.

Structural and Spectral Features of Selenium Nanospheres Produced by Se-Respiring Bacteria

“…Indeed, it is not just confined to the bacteria that are capable of dissimilatory reduction of Se oxyanions, as it has also been reported in Se-resistant bacteria. For example, electron micrographs of Wollinella succinogenes (43), Enterobacter cloacae (23), and Stenotrophomonas maltophilia (8) have all shown that spherical granules of Se(0) that were similar sizes were formed after cells were exposed to Se(IV) or Se(VI). Intracellular Se(0) granules have also been reported in cells of the photosynthetic bacterium Chromatium vinosum, although in this case the granules were generated by the lightinduced oxidation of H 2 Se rather than by the reduction of Se oxyanions (25).…”

Investigating the Effects of Se Solid Phase Substitution in Jarosite Minerals Influenced by Bacterial Reductive Dissolution

“…Their presence in only the treatments containing living bacteria suggests that the occurrence of elemental selenium is directly related to bacterial metabolism [33,[41][42][43]. Previous investigations have observed both intracellular [42,44,45] and extracellular [46,47] Se particles of various sizes and the precipitation mechanisms vary with the bacterial species. A prior study attributed intracellular elemental Se precipitation to a detoxification mechanism as Se 0 particles were observed within discrete internal membranes in Bacillus selenitireducens [42].…”

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.…”

“…They found that efficiency of growth varied with electron donor-acceptor combinations and that differences in energy coupling occurred with the various bacterial strains. Tomei et al (1992) adapted cultures of WoZineZZu succinogenes to grow in the presence of 1 mM Se032-or 10 mM SeO42-which were reduced to red, amorphous, elemental selenium after the culture reached the stationary growth phase. Bacterial cells taken from an active, selenium-reducing culture were examined by transmission electron microscopy and found to have large, electron-dense granules in the cytoplasm which consisted of selenium.…”

“…Microbial reduction of uranium and selenium for contaminant removal have been extensively studied (Lovley et al, 1991;Lovley and Phillips, 1992a;Lovley and Phillips, 1992b;Tomei et al, 1992;Tomei et al, 1995). Contaminant removal of chromium by microbial action has also been studied to a lesser degree (Fkde et al, 1994).…”