我国将在十二五期间大力发展核能,如何安全处置核废料是一个待解决的重要问题。六价铀是核废料的主要组成部分，某些微生物可以将高毒性、高水溶性的六价铀还原成低毒性、低水溶性的四价铀。利用微生物的这种特性来治理核废料是一种极具发展潜力的方法。在核废料环境下，微生物将受到高温、高辐射等逆境胁迫。但目前国际上用于治理核废料研究的微生物尚无抗辐射、耐高温的能力，导致其实际治理效果降低。本项目拟在抗辐射耐高温菌株Deinococcus radiodurans R1中表达来源于硫酸还原细菌Desulfovibrio desulfuricans G20的高效铀铬还原蛋白和铀铬还原操纵子，从而得到可在核废料环境中正常生长的铀铬还原菌株。工程菌株耐辐射与高温能力及还原铀铬的能力将会被鉴定。工程菌株也将被接种至土壤样品中以检测其实际生存与还原铀铬的能力。本项目将是国际上首次尝试构建工程菌株的方法来治理核废料的研究。

China will vigorously develop nuclear power during the twelfth five-year plan. Proper disposal of nuclear waste will be an important issue. Hexavalent uranium (U(VI)), a major component of nuclear waste,is highly toxic and water-soluble. Microorganisms can reduce U(VI) to tetravalent uranium (U(IV)) which has low toxicity and water solubility, and therefore immobilize uranium in the nuclear waste. This process has a great potential to remediate nuclear waste. Compared with other methods, microbial remediation is more cost-effective and rarely introduces secondary contamination. Microbes in nuclear waste environment will suffer radiation and heat stresses. However,most microbial strains currently used for nuclear waste treatment are not radiation/heat resistant, thus their reducing ability is greatly decreased. We will use Deinococcus radiodurans R1 which can tolerate high temperature and high radioactivity as host strain to express the highly efficient U(VI)/Cr(VI)-reducing protein and the U(VI)/Cr(VI)-reducing operon from the sulfate-reducing bacteria Desulfovibrio desulfuricans G20. The engineered strain might be able to grow under nuclear waste condition and reduce U(VI)/Cr(VI). We will measure the engineered strain's resistance to radiation and heat as well as its U(VI)/Cr(VI)-reducing ability in pure culture. The strain will also be inoculated into the soil sample to test its in situ suvival and U(VI)/Cr(VI) reducing ability.This will be the first attempt to construct an engineered microorganism for microbial nuclear waste remediation.