Biological nano-mineralization of Ce phosphate by Saccharomyces cerevisiae
Biological nano-mineralization of Ce phosphate by Saccharomyces cerevisiae
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DOI：
10.1016/j.chemgeo.2010.07.010
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发表时间：
2010-10-01
期刊：
影响因子：
3.9
通讯作者：
Utsunomiya, Satoshi
中科院分区：
文献类型：
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作者：
Jiang, Mingyu;Ohnuki, Toshihiko;Utsunomiya, Satoshi
为了了解稀土磷酸盐在微生物表面的纳米级矿化过程，我们研究了酿酒酵母在pH为3、4或5的Ce(III)溶液中暴露4-120h后固Ce的机理。采用了各种分析技术，包括配备能量色散X射线能谱的场发射扫描电子显微镜(FESEM-EDS)、透射电子显微镜(TEM)、电感耦合等离子体原子发射光谱(ICP-AES)、溶液中Ce的浓度随暴露时间的延长而降低，在pH为5的溶液中下降的速度比在pH为3或4时更快。FESEM、TEM和XAFS的分析表明，Ce(III)暴露42h后，酵母细胞上形成了具有独居石结构的针状Ce(III)磷酸盐纳米晶，尽管初始溶液中不含任何P物种。当pH从3增加到5时，Ce(III)磷酸盐纳米晶从50 nm左右长大到数百纳米。pH值越低，接种酵母细胞后溶液中磷的浓度越高，表明磷从酵母细胞中释放出来。这些结果表明，细胞表面吸附的Ce与酵母细胞内释放的P反应，形成了Ce(III)磷酸根纳米晶。微生物细胞表面的这种后吸附纳米结晶应该在限制稀土和三价放线元素在地质储存库中的长期迁移方面发挥关键作用。(C)2010爱思唯尔B.V.保留所有权利。
In order to understand the nanoscale mineralization process of REE phosphate on microorganism surfaces, we have investigated the mechanism underlying Ce sequestration by yeast Saccharomyces cerevisiae after exposure to Ce(III) solution for 4-120 h at pH 3, 4, or 5. A variety of analytical techniques have been employed, including field-emission scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (FESEM-EDS), transmission electron microscopy (TEM), inductively coupled plasma atomic emission spectrometry (ICP-AES), and synchrotron-based X-ray absorption fine structure (XAFS).Cerium concentration in solutions decreases as a function of exposure time and more rapidly at pH 5 than at pH 3 or 4. Analyses of the yeast cells by FESEM, TEM, and XAFS show that needle-shaped Ce(III) phosphate nanocrystallites with a monazite structure formed on the yeast cells by exposure to Ce(III) for 42 h, even though the initial solutions did not contain any P species. The Ce(III) phosphate nanocrystals grew from about 50 nm to hundreds of nanometers when pH increased from 3 to 5. Lower pH resulted in higher P concentration in the solution after the yeast cells were inoculated, indicating the release of P from the yeast cells. These results suggest that the sorbed Ce on the cell surfaces reacted with P released from inside the yeast cell, resulting in the formation of Ce(III) phosphate nanocrystallites. This post-sorption nanocrystallization on the microbial cell surface should play a key role in constraining the long-term migration of REEs and trivalent actinides in geological repositories. (C) 2010 Elsevier B.V. All rights reserved.