硒是生命必需的微量元素,以硒代半胱氨酸(Sec,第21位氨基酸)和硒代甲硫氨酸(Se-Met)的形式加入到硒蛋白(酶)中.人畜硒摄入过量或不足均会导致很多疾病.微生物参与了Se(-Ⅱ)、Se(0)、Se(Ⅳ)和Se(Ⅵ)等各种价态间的转化.本文主要综述微生物对硒的还原及其生物学意义.微生物对硒的还原包括同化还原、异化还原以及在还原基础上进行的硒的甲基化.硒的同化还原主要是形成各种硒蛋白,满足微生物自身对硒的需求,食源性微生物对人畜补硒具有重要意义.高浓度硒酸盐和亚硒酸盐则可促使微生物进行异化还原并形成单质纳米硒颗粒.有的微生物会将还原态的Sec和Se-Met进一步转化为挥发态的甲基化硒.硒的异化还原和甲基化都是解毒机制,在硒污染环境的治理中具有重要意义.最后,阐述了单质纳米硒在医药、生物传感器和治理重金属污染等方面的应用前景,以及微生物合成CdSe荧光量子点的应用.%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.
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