腐殖质AQS存在条件下腐败希瓦氏菌还原U(Ⅵ)的特性

谢水波^{1, 2}，张亚萍¹，刘金香²，刘迎九¹，李仕友²，王劲松¹，刘海燕¹

(1. 南华大学 城市建设学院，衡阳 421001；
2. 南华大学 铀矿冶生物技术国防重点学科实验室，衡阳 421001)

摘 要：在厌氧条件下，研究腐败希瓦氏菌还原U(Ⅵ)的特性，考察腐殖质模式物蒽醌-2-磺酸钠(AQS)浓度、金属离子(Cu²⁺ 、Ca²⁺、Cr⁶⁺等)与有毒有机物等对U(Ⅵ)还原的影响。结果表明：腐败希瓦氏菌可以利用一些有机酸盐作为电子供体，以AQS作为电子穿梭载体，进行醌呼吸，高效还原U(Ⅵ)。当AQS的浓度为0~2 mmol/L时，能显著加速U(Ⅵ)的还原过程；当AQS的浓度高于2 mmol/L时，随着AQS浓度从2 mol/L增加到10 mol/L，AQS与U(Ⅵ)竞争电子，明显抑制U(Ⅵ)的还原。同时，Ca²⁺和Cu²⁺对U(Ⅵ)的还原均表现出较强的抑制作用，Cu²⁺的抑制作用通过抑制呼吸链上脱氢酶的活性实现；但Mn²⁺和Cr⁶⁺ 对腐殖质还原U(Ⅵ)的影响较小，在60 h内，未观测到溶液中Cr⁶⁺浓度的明显变化。金属离子对还原U(Ⅵ)抑制作用的强度与其浓度正相关。环境中甲苯、三氯乙酸和对硝基苯酚等有毒有机物可以作为电子供体被腐败希瓦氏菌利用而降解，得到氧化降解，同时实现U(Ⅵ)的高效还原。

关键词：U(Ⅵ)；蒽醌-2-磺酸钠(AQS)；腐败希瓦氏菌；重金属；有毒有机物

Characteristics of reducing U(Ⅵ) by Shewanella putrefaciens in presence of anthraguinone-2-sulfonate (AQS)

XIE Shui-bo^{1, 2}, ZHANG Ya-ping¹, LIU Jin-xiang², LIU Ying-jiu¹, LI Shi-you², WANG Jin-song¹, LIU Hai-yan¹

(1. School of Urban Construction, University of South China, Hengyang 421001, China;
2. Key Discipline Laboratory for National Defence for Biotechnology in Uranium Mining and Hydrometallurgy,

Abstract:In the presence of anthraquinone-2-sulfonate(AQS), the reduction of U(Ⅵ) by Shewanella putrefaciens (S.putrefaciens) was investigated under anaerobic environment. The influences of different concentrations of AQS, heavy metal ions (e.g., Cu²⁺, Ca²⁺, Cr⁶⁺) and toxic organic compounds on the reduction of U(Ⅵ) were studied. The experimental results show S.putrefaciens is capable of utilizing various organic acids as electron donors and AQS as a electron shuttle vector to reduce U(Ⅵ) efficiently under anaerobic condition. At low concentration of 0-2 mol/L AQS is an effective accelerator for bioreduction of U(Ⅵ). However, when the concentration of AQS is more than 2 mmol/L, the effect of acceleration is gradually decreased with increasing concentration of AQS (2-10 mmol/L). AQS not only acts as an electron shuttle vector during the reduction process, but also as the competitor for electron from respiration chain. Meanwhile, Cu²⁺ has a strongly negative effect on the bioreduction of U(Ⅵ), as a typical inhibitor of dehydrogenases in respiration chain. A strong inhibition of bioreduction of U(Ⅵ) by Ca²⁺ is also observed. But, the reduction of U(Ⅵ) is only weakly affected by Cr^{6 +} and Mn²⁺, and in 60 h the significant change of the concentration of Cr⁶⁺ in the solution is not observed. The effect of metal ions on U(Ⅵ) reduction has a positive correlation with their concentrations. Some toxic organic compounds, such as toluenes, trichloroacetic acid and p-nitrophenol, are capable of being utilized as electron donors to reduce U(Ⅵ) efficiently by S.putrefaciens and be degraded at the same time.

Key words:U(VI); anthraquinone-2-sulfonate(AQS); Shewanella putrefaciens; heavy metal; toxic organic compounds