Reduction of Selenite to Red Elemental Selenium by Rhodopseudomonas palustris Strain N

Abstract

The trace metal selenium is in demand for health supplements to human and animal nutrition. We studied the reduction of selenite (SeO3 −2) to red elemental selenium by Rhodopseudomonas palustris strain N. This strain was cultured in a medium containing SeO3 −2 and the particles obtained from cultures were analyzed using transmission electron microscopy (TEM), energy dispersive microanalysis (EDX) and X ray diffraction analysis (XRD). Our results showed the strain N could reduce SeO3 −2 to red elemental selenium. The diameters of particles were 80–200 nm. The bacteria exhibited significant tolerance to SeO3 −2 up to 8.0 m mol/L concentration with an EC50 value of 2.4 m mol/L. After 9 d of cultivation, the presence of SeO3 2− up to 1.0 m mol/L resulted in 99.9% reduction of selenite, whereas 82.0% (p<0.05), 31.7% (p<0.05) and 2.4% (p<0.05) reduction of SeO3 −2 was observed at 2.0, 4.0 and 8.0 m mol/L SeO3 2− concentrations, respectively. This study indicated that red elemental selenium was synthesized by green technology using Rhodopseudomonas palustris strain N. This strain also indicated a high tolerance to SeO3 −2. The finding of this work will contribute to the application of selenium to human health.

Microbial selenite reduction with organic carbon and electrode as sole electron donor by a bacterium isolated from domestic wastewater

“…Notably, the growth of strain THL1 seemed to be inhibited by 20 mM initial selenite, where only 2.4% selenite was reduced after 3 d, corresponding to a selenite removal rate of 0.15 mM d À1 . The inhibition of microbial selenite reduction by selenite higher than 10 mM was also indicated previously for some bacteria (Ayano et al, 2014;Li et al, 2014;Zheng et al, 2014). This might be a disadvantage for using this strain in the bioremediation of high selenite-content wastewater.…”

“…The mechanisms of microbial reduction of selenate to selenite and selenite to elemental selenium through anaerobic respiration and detoxification have been characterized in both gram-negative and gram-positive bacteria (Debieux et al, 2011;Kuroda et al, 2011b;Schröder et al, 1997). Microbial reduction of selenite to elemental selenium is typically regarded as a detoxification mechanism, which has been observed in a wide range of microorganisms under both aerobic (Kuroda et al, 2011a;Zheng et al, 2014) and anaerobic conditions (Ayano et al, 2014;Basaglia et al, 2007;Hunter, 2014;Li et al, 2014). In all cases, the microbial detoxification of soluble selenium requires an adequate organic substrate as the electron donor.…”

Bacillus cereus, selenite-reducing bacterium from contaminated lake of an industrial area: a renewable nanofactory for the synthesis of selenium nanoparticles

“…It is significant to note that, in the literature, selenium nanoparticle producing bacteria are reported in wide range of environments under aerobic and anaerobic conditions including in sludge and sewerage (Mishra et al 2011). The anaerobic/anoxic bacteria include strains such as Selenihalanaerobacter shriftii DSSE1, Sulfurospirillum barnesii (Oremland et al 2004), Rhodopseudomonas palustris N (Li et al 2014), Veillonella atypica (Pearce et al 2008), Shewanella putrefaciens 200 (Jiang et al 2012), Shewanella sp. HN-41 (Lee et al 2007), etc.…”

“…Selenite-reducing bacteria have been isolated from a variety of environments including Mono Lake of California (Oremland et al 2004), Dead sea, a salt lake (Oremland et al 2004), Caspian sea of Iran (Shakibaie et al 2015), sediments of Cama-rones river from Atacama desert, Northern Chile (Torres et al 2012), activated sludge (Srivastava and Mukhopadhyay 2013), sludge of Taiyuan sewage plant, China (Li et al 2014), drainage slough from Nevada (Oremland et al 2004), and anaerobic granules from paper mill wastewater treating reactor (Jain et al 2015). In addition, from the soil of a antimony mine from Lengshuijiang, southern China (Zheng et al 2014), soil of a magnesite mine from Salem, India (Ramya et al 2015), soil of a coal mine from West Bengal, India (Dhanjal and Cameotra 2010), selenium laden agricultural soil of North-East Punjab, India (Bajaj et al 2012), soil of mangrove forest from Bhitarkanika, Orissa, India (Mishra et al 2011), rhizosphere soil of a selenium hyperaccumulator legume grown in seleniferous mine from Sardina, Italy (Lampis et al 2014), rhizosphere of wheat grown in herbicide contaminated soil (Dwivedi et al 2013), and rhizosphere of cereal plants grown in ash-derived volcanic soil of southern Chile (Durán et al 2015).…”

Biomimetic synthesis of selenium nanoparticles by Pseudomonas aeruginosa ATCC 27853: An approach for conversion of selenite

“…Earlier studies carried out on bacterial mediated synthesis of selenium nanoparticles, using Rhodopseudomonas palustris (Li et al, 2014), Shewanella sp. (Lee et al, 2007).…”