摘要
微生物诱导的U(Ⅵ)生物矿化会影响铀在环境中的化学形态和迁移行为,但目前对于生长和繁殖阶段的微生物诱导U(Ⅵ)矿化的动力学行为研究不多,相关的机制也不明确。本文从某拟用作极低放射性废物处置场场所的土壤中分离出1株芽孢杆菌Bacillus sp.dwc-2,考察了pH值、甘油磷酸钠(SGP)、U(Ⅵ)初始浓度等因素对Bacillus sp.dwc-2在生长繁殖过程中诱导U(Ⅵ)矿化动力学行为的影响,并对其矿化机制进行了探讨。结果表明,Bacillus sp.dwc-2可诱导U(Ⅵ)形成钠铀云母(NaUO_(2)PO_(4)·3H_(2)O)的晶体矿物,该过程作为一种酶促反应,受pH值、SGP浓度、U(Ⅵ)初始浓度等因素的显著影响;当U(Ⅵ)初始浓度从50 mg/L增加至150 mg/L时,刺激了处于生长迟滞期至对数期(培养0~12 h)菌体磷酸酶活性的表达和磷酸盐的代谢,使其诱导U(Ⅵ)的矿化行为发生在生长对数期(培养12 h);SGP浓度的增加促进了磷酸酶的催化反应速率,进而促进了U(Ⅵ)的矿化,当SGP的浓度从25 mmol/L增加到125 mmol/L时,Bacillus sp.dwc-2诱导U(Ⅵ)的矿化时间从其生长稳定期(培养24 h)提前至生长对数期(培养12 h);中性和碱性条件下,磷酸酶活性在生长迟滞期至对数期(培养0~12 h)快速增加,从而促进了磷酸盐的消耗和U(Ⅵ)的矿化,特别是在碱性条件下,沉积物在生长对数期(培养8 h)时即转化为明显的晶体矿物。
The U(Ⅵ)biomineralization on microorganisms will affect the chemical form and migration behavior of uranium in the environment.However,there are few studies on the kinetic behavior and the relevant mechanism of U(Ⅵ)biomineralization in the growth of microorganisms.In this work,the effects of pH values,sodium glycerophosphate(SGP)and U(Ⅵ)concentration on the biomineralization behavior of U(Ⅵ)in the growth of Bacillus sp.dwc-2,a bacterial strain isolated from a potential(ultra-)low radioactive waste disposal site,and the possible mechanism were investigated.The results indicate that the formation of sodium uranyl phosphate(NaUO_(2)PO_(4)·3H_(2)O)induced by Bacillus sp.dwc-2 as an enzyme-catalyzed reaction in the presence of factors such as pH value,SGP concentration,and initial U(Ⅵ)concentration.The increase of U(Ⅵ)concentration(50-150 mg/L)stimulates the expression of phosphatase activity and phosphate metabolism at the initial stage of biomineralization(0-12 hours),leading to a shift of biomineralization induced by Bacillus sp.dwc-2 at the 12th hour.The increase of the SGP concentration could promote the catalytic reaction rate of phosphatase,and then promote the U(Ⅵ)biomineralization.When the SGP concentration increases from 25 mmol/L to 125 mmol/L,the time of biomineralization induced by Bacillus sp.dwc-2 advances from 24 hours to 12 hours.The phosphatase activity increases rapidly at the initial stage of biomineralization(0-12 hours)under neutral and alkaline conditions,thus promoting the consumption of phosphate and the U(Ⅵ)biomineralization.Especially under alkaline condition,the sediment is transformed into obvious crystal minerals at the 8th hour.The above research results are helpful to better understand the behavior and mechanism of uranium biomineralization,and also have reference value for bioremediation of uranium contaminated environment.
作者
郭豫齐
涂鸿
李飞泽
兰图
杨吉军
杨远友
刘宁
廖家莉
GUO Yuqi;TU Hong;LI Feize;LAN Tu;YANG Jijun;YANG Yuanyou;LIU Ning;LIAO Jiali(Key Laboratory of Radiation Physics and Technology of Ministry of Education,Institute of Nuclear Science and Technology,Sichuan University,Chengdu 610064,China)
出处
《原子能科学技术》
EI
CAS
CSCD
北大核心
2023年第10期1878-1888,共11页
Atomic Energy Science and Technology
基金
国家自然科学基金(21876123)。
