Abstract:Selenium is an essential trace element for life, incorporates into selenoproteins (seleno-enzymes) in the form of selenocysteine (Sec, also referred to as the 21st protein amino acid) and selenomethionine (Se-Met). Either selenium over-intake or deficiency will lead to the occurrence of many diseases. Microorganisms are involved in the transformation of different selenium speciation including Se(?II), Se(0), Se(IV) and Se(VI). Here we mainly reviewed the reduction of selenium in microorganisms. The reduction of selenium by microbes include assimilation reduction and dissimilation reduction. Selenoproteins could be produced via the pathway of the selenium assimilation reduction, which is benefit for the selenium enrichment through food chain. Higher concentration of selenate and selenite would promote the process of selenium dissimilation reduction and the formation of selenium nanoparticles in some microbes. Both selenium methylation and the formation of selenium nanoparticles were mechanisms of detoxification, and would provide an economical and “green” solution to the bioremediation of environmental selenium contamination. Finally, the potential applications of biogenic selenium nanoparticles (bio-SeNPs) in medicine, biosensor and heavy metal contamination bioremediation were discussed. The biosynthesis of CdSe quantum dots by microbes and its biological applications were also introduced.
