微生物与铯的相互作用及其在放射性核素污染环境修复中的应用潜力

Interaction of microorganism with caesium and its potential application in bioremediation of radionuclide contamination

含放射性核素的废物在排放前必须进行有效的处理。铯是核电站排放的放射性物质之一。现有的除铯技术,如沸石吸附、离子交换等方法成本较高。利用微生物技术去除铯是目前可以考虑的替代方案,铯具有的独特化学性质决定了铯与微生物之间的相互作用机理不同于其它金属/放射性核素。据报道,自然界中存在大量的微生物可以吸收铯,但不同种类的微生物,其吸收量差别很大,微生物对铯的吸收量受一些环境因素的影响,如操作系统(分批式或连续流)、菌体的固定化、pH值,特别是其它单价阳离子(如K^+、Na^+)存在与否等。微生物对铯吸收量的差别可能与其单价阳离子转移系统对铯的亲合力有关,通过现代生物技术手段可以分离筛选出对铯具有高度亲合力的微生物。此外,控制微生物的生理状态也可以改变其对铯的亲合力。微生物方法去除铯在放射性核素污染环境的生物修复中具有实用潜力。

The removal of Cs from industrial waste effluents prior to discharge is necessary. Caesium is one of the radio-contaminants discharged from nuclear power plants. Current technologies for Cs removal, such as zeolite adsorption, ion-exchange method, are expensive. Microbial technology may present a cheap alternative. The distinct chemical properties of Cs indicate that the interaction mechanism of caesium-microorganism is different from that of other metals/radionuclides. It has been reported that a number of microorganisms can uptake caesium. However, uptake levels vary markedly in different organisms and are strongly influenced by a number of factors, such as the operational mode (batch or continuous- flow systems), biomass immobilization, pH, and particularly the presence of other monovalent cations, such as K+ and Na+. The differences in Cs+ uptake capacities of different microorganisms appear to be attributable to differences in the affinity of monovalent cation transport systems for Cs +. By means of modern biotechnological methods, microorganisms with particularly high affinity for Cs + can be isolated. Moreover, manipulation of physiological states of microorganisms can also change the affinity for Cs + . Removal of caesium by biotechnological methods has potential application in bioremediation of radionuclides-contaminated environment.