Gilson Emily R, Huang Shan, Jaffé Peter R
Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ, 08544, USA.
Biodegradation. 2015 Nov;26(6):475-82. doi: 10.1007/s10532-015-9749-y. Epub 2015 Nov 2.
This study investigated the possibility of links between the biological immobilization of uranium (U) and ammonium oxidation under iron (Fe) reducing conditions. The recently-identified Acidimicrobiaceae bacterium A6 (ATCC, PTA-122488) derives energy from ammonium oxidation coupled with Fe reduction. This bacterium has been found in various soil and wetland environments, including U-contaminated wetland sediments. Incubations of Acidimicrobiaceae bacteria A6 with nontronite, an Fe(III)-rich clay, and approximately 10 µM U indicate that these bacteria can use U(VI) in addition to Fe(III) as an electron acceptor in the presence of ammonium. Measurements of Fe(II) production and ammonium oxidation support this interpretation. Concentrations of approximately 100 µM U were found to entirely inhibit Acidimicrobiaceae bacteria A6 activity. These results suggest that natural sites of active ammonium oxidation under Fe reducing conditions by Acidimicrobiaceae bacteria A6 could be hotspots of U immobilization by bioreduction. This is the first report of biological U reduction that is not coupled to carbon oxidation.
本研究调查了在铁还原条件下铀（U）的生物固定与铵氧化之间存在联系的可能性。最近鉴定出的嗜酸微生物科细菌A6（美国典型培养物保藏中心，PTA - 122488）通过铵氧化与铁还原耦合获取能量。这种细菌已在包括受铀污染的湿地沉积物在内的各种土壤和湿地环境中被发现。用绿脱石（一种富含铁（III）的粘土）和大约10 μM铀对嗜酸微生物科细菌A6进行培养表明，在有铵存在的情况下，这些细菌除了能利用铁（III）外，还能利用铀（VI）作为电子受体。铁（II）生成量和铵氧化的测量结果支持了这一解释。发现大约100 μM的铀浓度能完全抑制嗜酸微生物科细菌A6的活性。这些结果表明，在铁还原条件下，嗜酸微生物科细菌A6进行活跃铵氧化的天然场所可能是通过生物还原固定铀的热点区域。这是关于不与碳氧化耦合的生物铀还原的首次报道。
