School of Nuclear Science and Technology, Lanzhou University, No. 222, Tianshui South Road, Chengguan District, Lanzhou 730000, China.
Chemosphere. 2017 May;175:161-169. doi: 10.1016/j.chemosphere.2017.02.035. Epub 2017 Feb 7.
Biosorption of heavy metal elements including radionuclides by microorganisms is a promising and effective method for the remediation of the contaminated places. The responses of live Saccharomyces cerevisiae in the toxic uranium solutions during the biosorption process and the mechanism of uranium biomineralization by cells were investigated in the present study. A novel experimental phenomenon that uranium concentrations have negative correlation with pH values and positive correlation with phosphate concentrations in the supernatant was observed, indicating that hydrogen ions, phosphate ions and uranyl ions were involved in the chernikovite precipitation actively. During the biosorption process, live cells desorb deposited uranium within the equilibrium state of biosorption system was reached and the phosphorus concentration increased gradually in the supernatant. These metabolic detoxification behaviours could significantly alleviate uranium toxicity and protect the survival of the cells better in the environment. The results of microscopic and spectroscopic analysis demonstrated that the precipitate on the cell surface was a type of uranium-phosphate compound in the form of a scale-like substance, and S. cerevisiae could transform the uranium precipitate into crystalline state-tetragonal chernikovite [H(UO)(PO)·8HO].
微生物吸附包括放射性核素在内的重金属元素是污染场所修复的一种很有前途和有效的方法。本研究调查了活酿酒酵母在生物吸附过程中有毒铀溶液中的反应以及细胞铀生物矿化的机制。观察到一个新的实验现象，即在铀的浓度与上清液中的 pH 值呈负相关，与磷酸盐浓度呈正相关，这表明氢离子、磷酸盐离子和铀酰离子积极参与了沥青铀矿的沉淀。在生物吸附过程中，活细胞在达到生物吸附体系平衡状态时会解吸已沉积的铀，而上清液中的磷浓度会逐渐增加。这些代谢解毒行为可以显著减轻铀的毒性，并更好地保护细胞在环境中的存活。微观和光谱分析的结果表明，细胞表面的沉淀物是一种磷铀化合物，呈鳞片状物质，酿酒酵母可以将铀沉淀物转化为结晶态四方沥青铀矿[H(UO)(PO)·8HO]。
