Nonreductive Biomineralization of Uranium(VI) Phosphate Via Microbial Phosphatase Activity in Anaerobic Conditions
Nonreductive Biomineralization of Uranium(VI) Phosphate Via Microbial Phosphatase Activity in Anaerobic Conditions
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DOI：
10.1080/01490450903060780
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发表时间：
2009-01-01
影响因子：
2.3
通讯作者：
Taillefert, Martial
中科院分区：
文献类型：
--
作者：
Beazley, Melanie J.;Martinez, Robert J.;Taillefert, Martial
从美国能源部(DOE)的土壤和地下水中修复铀是一个重大的环境问题，而生物修复作为一种将铀固定在地下的策略已经显示出巨大的潜力。在厌氧条件下，将U(VI)生物还原为不溶性U(IV)铀矿是一种有效的生物修复过程。然而，在一些污染地区发现的高浓度硝酸盐和低pH值限制了微生物还原铀的效率。在本研究中，研究了在厌氧条件下，在高硝酸盐和低pH条件下，微生物磷酸酶活性促进的非还原铀的生物矿化，作为一种生物还原U(VI)的方法。兼性厌氧菌Rahnella sp.从美国能源部橡树岭野外研究中心(ORFRC)的土壤中分离到的Y9602菌株能够在3-磷酸甘油(G3P)作为唯一碳源和磷源的情况下，以硝酸盐为末端电子受体进行厌氧呼吸，并在pH为5.5的合成地下水中水解足够的磷酸盐，120h后可使95%的总铀沉淀出来。经同步加速器X射线衍射和X射线吸收光谱鉴定，该矿物为铀(VI)奥陶石型矿物--切尔尼科夫石。这项研究的结果表明，在受污染的地下表面，如在ORFRC，高浓度的硝酸盐和低pH可能限制铀的生物还原，在提供有机磷的来源用于生物修复的情况下，U(VI)磷酸盐矿物的生物矿化可能是更有吸引力的就地修复方法。
The remediation of uranium from soils and groundwater at Department of Energy (DOE) sites across the United States represents a major environmental issue, and bioremediation has exhibited great potential as a strategy to immobilize U in the subsurface. The bioreduction of U(VI) to insoluble U(IV) uraninite has been proposed to be an effective bioremediation process in anaerobic conditions. However, high concentrations of nitrate and low pH found in some contaminated areas have been shown to limit the efficiency of microbial reduction of uranium. In the present study, nonreductive uranium biomineralization promoted by microbial phosphatase activity was investigated in anaerobic conditions in the presence of high nitrate and low pH as an alternative approach to the bioreduction of U(VI). A facultative anaerobe, Rahnella sp. Y9602, isolated from soils at DOE's Oak Ridge Field Research Center (ORFRC), was able to respire anaerobically on nitrate as a terminal electron acceptor in the presence of glycerol-3-phosphate (G3P) as the sole carbon and phosphorus source and hydrolyzed sufficient phosphate to precipitate 95% total uranium after 120 hours in synthetic groundwater at pH 5.5. Synchrotron X-ray diffraction and X-ray absorption spectroscopy identified the mineral formed as chernikovite, a U(VI) autunite-type mineral. The results of this study suggest that in contaminated subsurfaces, such as at the ORFRC, where high concentrations of nitrate and low pH may limit uranium bioreduction, the biomineralization of U(VI) phosphate minerals may be a more attractive approach for in situ remediation providing that a source of organophosphate is supplied for bioremediation.