Bacterial Diversity in the Hyperalkaline Allas Springs (Cyprus), a Natural Analogue for Cementitious Radioactive Waste Repository
Bacterial Diversity in the Hyperalkaline Allas Springs (Cyprus), a Natural Analogue for Cementitious Radioactive Waste Repository
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DOI：
10.1080/01490451.2014.961107
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发表时间：
2016-02
影响因子：
2.3
通讯作者：
Athanasios Rizoulis;A. Milodowski;K. Morris;J. Lloyd
中科院分区：
文献类型：
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作者：
Athanasios Rizoulis;A. Milodowski;K. Morris;J. Lloyd
人们对中等水平放射性废物的高碱性水泥质地质处置设施与地圈之间界面上形成的生物地球化学梯度知之甚少。此外，关于可能在这些环境中繁殖的微生物及其在生物矿化、气体消耗和产生、金属循环以及放射性核素形态和溶解度中的作用的信息也很少。在这项研究中，我们调查了土著微生物群落的系统发育多样性和潜在的碱金属还原样品中收集的天然类似物水泥放射性废物库，超碱性阿拉斯泉（pH值高达11.9），特罗多斯山，塞浦路斯。该遗址位于一个超基性岩蛇绿混杂岩中，这些超基性岩正在经历活跃的低温蛇纹石化作用，从而导致超碱性条件。16S rRNA克隆和测序表明，在这种天然高pH环境中存在着遗传多样性的微生物群落，包括噬氢菌属物种。这表明，耐碱性氢氧化微生物可能会殖民化的碱性地质处置库，这是预测富含分子H2，作为过程的结果，包括钢铁腐蚀和纤维素生物降解的废物。此外，微生物金属还原证实在碱性pH值在本研究中的富集缩影和纯培养的细菌菌株属于类芽孢杆菌属和嗜碱菌属。总体而言，这些数据表明，在高pH值环境中可能会发生各种各样的微生物过程，这与中等水平废物地质处置过程中预期的微生物过程一致。其中许多，包括气体代谢和金属还原，对放射性废物的长期地质处置有明显的影响。
The biogeochemical gradients that will develop across the interface between a highly alkaline cementitious geological disposal facility for intermediate level radioactive waste and the geosphere are poorly understood. In addition, there is a paucity of information about the microorganisms that may populate these environments and their role in biomineralization, gas consumption and generation, metal cycling, and on radionuclide speciation and solubility. In this study, we investigated the phylogenetic diversity of indigenous microbial communities and their potential for alkaline metal reduction in samples collected from a natural analogue for cementitious radioactive waste repositories, the hyperalkaline Allas Springs (pH up to 11.9), Troodos Mountains, Cyprus. The site is situated within an ophiolitic complex of ultrabasic rocks that are undergoing active low-temperature serpentinization, which results in hyperalkaline conditions. 16S rRNA cloning and sequencing showed that phylogenetically diverse microbial communities exist in this natural high pH environment, including Hydrogenophaga species. This indicates that alkali-tolerant hydrogen-oxidizing microorganisms could potentially colonize an alkaline geological repository, which is predicted to be rich in molecular H2, as a result of processes including steel corrosion and cellulose biodegradation within the wastes. Moreover, microbial metal reduction was confirmed at alkaline pH in this study by enrichment microcosms and by pure cultures of bacterial isolates affiliated to the Paenibacillus and Alkaliphilus genera. Overall, these data show that a diverse range of microbiological processes can occur in high pH environments, consistent with those expected during the geodisposal of intermediate level waste. Many of these, including gas metabolism and metal reduction, have clear implications for the long-term geological disposal of radioactive waste.