胞外聚合物在腐败希瓦氏菌处理铀污染地下水中的作用

以模拟铀污染地下水为对象，采用腐败希瓦氏菌对其进行了固定铀实验，利用单粒子 电感耦合等离子体质谱（SP ICP MS）、3种胞外聚合物（EPS）提取方法和碳酸氢钠 硝酸分级提取法表征了腐败希瓦氏菌和EPS中铀的含量和赋存形态，并采用傅立叶红外光谱（FT IR）技术分析了EPS与铀反应前后的变化。结果表明，阳离子交换树脂（CER）法适用于表征EPS中的铀含量及形态，EPS中的铀可占腐败希瓦氏菌固定铀总量的(140±10)%。SP ICP MS分析表明，CER法获得的EPS中颗粒铀是其主要形态，EPS在固定铀的过程中，既涉及到生物吸附，也涉及到生物矿化。FT IR分析进一步说明生物吸附时,铀可与EPS中的羧基官能团结合。以上结果表明，EPS在腐败希瓦氏菌固定铀的过程中发挥了重要作用。

Role of Extracellular Polymeric Substance in Uranium Removal from Groundwater by Shewanella putrefaciens

In this paper, batch experiments were carried out by treating simulated uranium contaminated groundwater with Shewanella putrefaciens, and uranium in extracellular polymeric substances (EPS) was extracted using three different methods. Moreover, speciation of uranium in EPS was investigated by filtration and inductively coupled plasma with mass spectroscopy. The sequential NaHCO3 and HNO3 extraction approach was applied to fractionate uranium in the Shewanella putrefaciens during uranium immobilization reaction was performed. The changes before and after the reaction between EPS and uranium were characterized by Fourier transform infrared spectrometer (FT IR). The results show that the cation exchange resin (CER) method was suitable for characterizing the uranium content and form in EPS, and about (140±10)% of the total uranium immobilized by Shewanella putrefaciens was found to be present in EPS. The analysis of single particle inductively coupled plasma mass spectrometry (SP ICP MS) shows that the particle uranium in the EPS obtained by the CER method is the main form. Biosorption and biomineralization are confirmed to be involved in the uranium immobilization by EPS. The FT IR spectra further show that uranium may combine with the carboxyl functional group in EPS. The findings of this study imply the important roles of EPS in the immobilization of uranium in groundwater using Shewanella putrefaciens.