细菌还原氧化态硒产生红色单质硒的研究进展

硒是一种生命必需的微量元素,但高浓度时毒性较强且会造成环境污染。许多细菌可以将亚硒酸盐(SeO32-)或硒酸盐(SeO42-)等毒性较高的氧化态硒还原为毒性较小的红色单质硒(Se°),形成硒-蛋白复合物,它们对于获得最佳补硒方式和治理硒环境污染具有应用潜力。近年来,关于这一生物还原过程,人们进行了大量的研究,包括碳源、氧气、元素硫、谷胱甘肽以及一些氧化还原酶和膜转运蛋白等在内的多种物质都被发现可能影响或参与了细菌对硒的代谢。综述了细菌进行生物还原氧化态硒的影响因素及不同细菌产生红色单质硒机理的研究进展。

Progress in research of the product of the red elemental selenium reduced from selenium oxyanions by bacteria

Selenium (Se) is a naturally occurring trace element. It is essential for humans and animals but is very toxic at higher concentrations and will make the selenium pollution. In four inorganic states of selenate SeO4(2-) (VI)], selenite SeO3(2-) (IV)], elemental selenium Se0 (0)] and selenide Se2- (-II)], selenium oxyanions including selenite and selenate are well known to be more bioavailable but higher toxic than other forms. Many bacteria have the capacity to reduce selenium oxyanions to red elemental ground granule, called red elemental selenium, which is likely to be Se-protein compound. It has lower toxicity comparing with selenite, but when the size is at 5-200 nm, its bioavailability to selenite was similar in terms of inducing seleno-enzymes in cultured cells and in Se-deficient rats. This provides the potential to gain the best manner to supply selenium for organisms and solve the pollution of selenium. So far, series of researches have been made to study this bacterial reduced process. Many substances such as carbon source, oxygen, elemental sulfur, glutathione, some oxidoreductases and transfer protein in membrane were found to affect or participate this biological dissimilatory reduction. This review presents the discovery of the biomorphic red elemental selenium, factors affecting the bacterial reduction of the selenium oxyanions, and the possible pathways to form red elemental selenium in bacteria.