Abstract Deep geological repository (DGR) is one of the internationally accepted options to dispose radioactive wastes. Bentonite formations from Almeria, Spain, were selected as reference material for artificial barriers for the future Spanish repository. However, the safety of this long-term disposal could be compromised not only by physicochemical factors but also by microbial processes. The highly radioactive waste must be safely stored at least for 100,000 years for the radioactivity to decrease to similar levels to those of natural uranium. To simulate a scenario where the mobilization of radionuclides from the repository to the host formations may occur, long-term microcosms were studied. After being exposed to uranyl nitrate for 5 months, the response of the bentonite microbial community to the addition of this radionuclide was evaluated. High throughput 16S rRNA gene sequencing revealed that the structure of the microbial community after the uranyl nitrate treatment differs to that of the control microcosms. The microbial diversity was dominated by Firmicutes and Proteobacteria. Moreover, after the uranyl nitrate treatment OTUs annotated as Paracoccus and Bacillus were highly enriched. The mineralogy of bentonites was not affected by the uranyl nitrate treatment as was demonstrated by X-ray diffraction analysis. In addition, the study of uranium-bacteria interaction revealed the ability of isolates to biomineralize uranium as uranium phosphate mineral phases. Thus, the changes induced by the release of uranium in the microbial population may also affect the mobility of this radionuclide, making it less mobile and therefore less harmful for this environment.

中文翻译：

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硝酸铀酰诱导膨润土微观世界微生物群落变化

摘要 深地质处置库（DGR）是国际公认的放射性废物处置方案之一。西班牙阿尔梅里亚的膨润土地层被选为未来西班牙储存库人工屏障的参考材料。然而，这种长期处置的安全性不仅会受到物理化学因素的影响，还会受到微生物过程的影响。高放射性废物必须至少安全储存 100,000 年，才能将放射性降至与天然铀相似的水平。为了模拟可能发生放射性核素从储存库移动到宿主地层的情景，研究了长期微观世界。在暴露于硝酸铀酰 5 个月后，评估了膨润土微生物群落对添加这种放射性核素的反应。高通量 16S rRNA 基因测序显示，硝酸铀酰处理后微生物群落的结构与对照微观世界不同。微生物多样性以厚壁菌门和变形菌门为主。此外，在硝酸铀酰处理后，注释为副球菌和芽孢杆菌的 OTU 高度富集。正如 X 射线衍射分析所证明的那样，膨润土的矿物学不受硝酸铀酰处理的影响。此外，铀-细菌相互作用的研究揭示了分离物将铀生物矿化为磷酸铀矿物相的能力。因此，微生物种群中铀的释放引起的变化也可能影响这种放射性核素的流动性，使其流动性较低，因此对这种环境的危害较小。