基于XAFS技术研究抗性真菌对U(VI)和As(V)的协同转化机理

In recent years, the problems of radionuclides and heavy metals pollution caused by uranium mining give rise to widespread concern. Studies have shown that the resistant fungi play a critical role in transformation of U(VI) or As(V). We have screened out many strains of highly resistant fungi to U(VI) and As(V) from uranium contaminated soil, but the molecular mechanism of cooperative transformation of U(VI) and As(V) by fungi are not yet clear. The project intends to illuminate intracellular and extracellular fungal resistant mechanism of U(VI) and As(V) by detecting expression level of intracellular metallothionein (MT) and glutathione (GSH) and concentration and composition of extracellular polymer substance (EPS). X-ray absorption fine structure (XAFS) will be used to detect U(VI) and As(V) speciation and coordination structure of intracellular and extracellular U(VI) and As(V), reaction product/precipitation and interaction between U(VI) and As(V) and MT, GSH and EPS under different circumstances. The results will investigate effects of MT, GSH and EPS on cooperative transformation of U(VI) and As(V) and illuminate cooperative transformation mechanisms of U(VI) and As(V) by resistant fungi. This research results will provide experimental data and theoretic bases for mycoremediation of uranium mine and metallurgy pollution.

近年来，铀矿开采中放射性核素和重金属污染问题引起人们广泛关注。研究表明，抗性真菌对U(VI)或As(V)转化起至关重要的作用。申请人前期从铀矿污染土壤中筛选出多株对U(VI)和As(V)高抗性真菌，但对其协同转化环境中U(VI)和As(V)的分子机理尚未明确。本项目通过分析在U(VI)和As(V)胁迫下真菌胞内金属硫蛋白(MT)和谷胱甘肽(GSH)表达量以及胞外聚合物(EPS)浓度和成分变化，阐明真菌胞对U(VI)和As(V)的抗性机理。采用X射线吸收精细结构(XAFS)技术研究不同环境条件下U(VI)和As(V)在真菌胞内外、产物/沉淀以及提取的MT、GSH和EPS与U(VI)和As(V)相互作用的微观结构和化学形态。探讨MT、GSH和EPS对协同转化U(VI)和As(V)作用，阐明真菌协同转化U(VI)和As(V)的分子机理。本项目研究结果将为真菌修复铀矿治污染提供实验数据与理论依据。

铀矿开采中放射性核素和重金属离子的富集与转化对于评估和分析铀尾矿的污染治理具有重要的意义。本项目从铀矿污染土壤中筛选出11株对U(VI)和As(V)高抗性的真菌，通过静态富集实验研究反应时间、pH值、离子强度和反应温度等对真菌富集U(VI)和As(V)的影响；通过分析在U(VI)和As(V)胁迫下真菌的氧化应激水平，抗氧化酶（SOD和CAT）、菌丝内外形貌，生物量以及菌丝内有机酸（草酸和柠檬酸）和硫醇物质（NP-SH和PB-SH）含量变化，阐明真菌对U(VI)和As(V)的抗性机理。采用X射线吸收精细结构(XAFS)和XPS等技术研究不同环境条件下在U(VI)和As(V)胁迫下真菌胞内外、产物/沉淀与U(VI)和As(V)相互作用的微观结构和化学形态。阐明真菌协同转化U(VI)和As(V)的分子机理。本项目研究结果将为真菌修复铀矿治污染提供实验数据与理论依据。