奥奈达希瓦氏菌MR-1还原U(VI)的特性及影响因素

探讨了在腐殖质模式物蒽醌?2?磺酸钠(AQS)存在条件下,奥奈达希瓦氏菌MR-1的还原U(VI)特性.结果表明,在厌氧环境下奥奈达希瓦氏菌以AQS为电子穿梭载体,利用电子供体高效还原U(VI).当菌体投加量为1.2×109 个时,其还原铀的效率达95.09%; AQS的浓度低于0.5mmol/L时有利于MR-1菌厌氧还原U(VI),AQS浓度的升高U(VI)的还原明显受到抑制.当U(VI)初始浓度为30.0mg/L时,分别以甲酸盐、乙酸盐和乳酸盐为电子供体,经过7d后其还原率分别达到95.37%、92.41%和95.65%.金属离子(Cu2+、Mn2+、Ca2+)、有毒有机物等对U(VI)还原产生影响.当Ca2+的浓度为2.0mmol/L时,对U(VI)的还原有微弱的促进作用,而当Cu2+和Mn2+浓度为2.0mmol/L时,则存在较强的抑制作用.奥奈达希瓦氏菌也能利用环境中甲苯、三氯乙酸、顺丁烯二酸等有毒物质高效还原U(VI),同时使有毒物质得到降解.扫描电子显微镜(SEM)和电子能谱(EDS)分析结果表明,奥奈达希瓦氏菌菌体中沉积了铀元素.

Characteristics of reducing U(VI) by Shewanella oneidensis MR-1and its impact factors

Characteristics and reaction conditions of anaerobic reduction by the Shewanella oneidensis MR-1in the presence of anthraquinone-2-sulfonate (AQS) were evaluated. The results showed that U(VI) could be efficiently reduced by S. oneidensis MR-1utilizing AQS and electron donors under the anaerobic conditions. Its reduction efficiency reached 95.09% when the dosage of MR-1was 1.2′109. The efficiency of U(VI) bioreduction increased when the concentration of AQS was below 0.5mmol/L, and inhibited when it exceeded 0.5mmol/L. When the initial concentration of U (VI) was 30mg/L, uranium reduction rates were 95.37%, 92.41% and 95.65% while using formate, acetate and lactate respectively. Metal ions (Cu2+, Mn2+, Ca2+) and toxic organics had impacts on the reduction of U (VI). Ca2+ acted as a weak role in promoting the reduction, however, equal concentrations of Cu2+ and Mn2+ played a strong inhibitory effect. Toxic organic compounds were available to reduce U (VI) efficiently by S. oneidensis MR-1and get degraded at the same time. Characterizations with Scanning Electron Microscope (SEM) and Energy dispersive spectroscopy (EDS) indicated the deposition of U element on the cell of S. oneidensis.