Selenium uptake by sulfur-accumulating bacteria

Selenium speciation in Lower Cambrian Se-enriched strata in South China and its geological implications

“…Only a few studies have identified Se(0) formation under abiotic conditions in pure laboratory simulations (Myneni et al, 1997;Charlet et al, 2007). Howevere, the absence of Se(0) and abundance of Se(-II) associated with sulfides/ selenides in the sulfide layer indicated two possible pathways for Se(-II): (1) the product of the further reduction from Se(VI) and Se(IV) through Se(0) by the presence of bacteria such as B. selenitreducens (Herbel et al, 2003) and D. desulfuricans (Nelson et al, 1996); and (2) injection of reducing hydrothermal fluids with abundant Se(-II). In addition, the much higher proportion of Se(-II) associated with sulfides/selenides compared to host black shales, also indicates that anoxic conditions with abundant organic material dominated enriching Se into the Ni-sulfides/MoSC phase.…”

“…Besides microbial reduction, the formation of elemental Se can also take place in abiotic processes (Myneni et al, 1997;Charlet et al, 2007;Chen et al, 2009). The most reduced form of Se, selenide(Se(-II)), forms either from reduction of Se(IV), Se(VI) and Se(0) in anoxic sediments and seems to require the presence of bacteria such as Bacillus selenitreducens (Herbel et al, 2003) and Desulfovibrio desulfuricans (Zehr and Oremland, 1987;Nelson et al, 1996). Subsequently, Se(-II) is immobilized on the sediment surface, also within the sediments by free metal ions (Zhang and Frankenberger, 2003b).…”

The microbial impact on the sorption behaviour of selenite in an acidic, nutrient-poor boreal bog

“…The behaviour of selenium in the environment is influenced by several factors such as pH, chemical form, soil mineral composition, redox conditions, as well as micro-organisms (Nakamaru and Altansuvd, 2014;Sarret et al, 2005;Nelson et al, 1996;Oremland et al, 2004;de Souza et al, 1999). In the environment selenium occurs with different oxidation states forming selenide (Se 2À ), elemental Se (Se 0 ), selenite (SeO 3 2À ), selenate (SeO 4 2À ), and organic Se (Kausch et al, 2012;Pezzarossa et al, 1999).…”

Structural and spectral features of selenium nanospheres produced by Se-respiring 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).…”