抗铅锌功能菌生长菌株和干菌体吸附Pb^(2+)、Zn^(2+)性能优化及机理分析

Biosorption of Pb(Ⅱ) and Zn(Ⅱ) by the growing strain/dry biomass of a resistant fungus: optimization and mechanism studies

【目的】针对湖南资兴铅锌矿污染问题,筛选本土耐性菌株用作生物修复。【方法】供试菌株J3筛选自湖南资兴铅锌矿区的尾砂矿矿渣,利用正交实验分析其生长菌株及干菌体最佳吸附条件以优化其吸附效果,同时对相关数据进行动力学拟合以探讨其吸附机理,最后结合形态观察和18S r RNA基因序列分析对其进行分类鉴定。【结果】在最佳条件下,J3生长菌株对Pb2+和Zn2+的去除率分别为92.2%和87.7%;干菌体对Pb2+和Zn2+去除率分别为72.6%和23.8%,反应动力学模型研究表明,生长菌株吸附过程中吸附速率受重金属浓度影响,对Zn2+吸附主要为颗粒内扩散作用;干菌体对Pb2+吸附推测为膜扩散和颗粒内扩散作用,而对Zn2+的吸附则由膜扩散控制。根据形态特征和系统发育分析,J3初步鉴定为虫生轮枝菌。【结论】生长菌株吸附效果好于干菌体,二级动力学方程拟合结果可为生物吸附反应器的设计提供理论参考和实践指导。

[Objective] The aim of this study is to screen lead-zinc tolerant fungus for the bioremediation of heavy metal pollution in Zixing, Hunan. [Methods] The fungus J3 which was isolated from the local tailing of lead-zinc deposit was used. Orthogonal test was carried out for studying adsorption conditions optimization and biosorption mechanism was discussed by kinetics simulation. And morphological characteristics and 18S rRNA gene sequence analysis were used for identification. [Resultsl Under the optimal conditions, the results showed that the removal rate of Pb2＋ and Zn2＋ by growing strains reached 92.2% and 87.7%, while the removal rate of Pb2＋ and Zn2＋ by dry biomass was 72.6% and 23.8%. The results of kinetics study indicated that the absorption by growing strain was affected by the concentration of Pb2＋ and Zn2＋. The intra-particle diffusion was the main rate-controlling step for the adsorption of Zn2＋. The adsorption of Pb2＋ by dry biomass may be affected with membrane diffusion and intra-particle diffusion at the same time. And the adsorption process of Zn2＋ was controlled by membrane diffusion. According to the morphological characterization and phylogenetic tree, J3 was preliminarily identified as Verticillium insectorum. [Conclusion] The growing strain had better adsorption effect than the dry. The result which fitted to the second-order equation can provide the basis and guidance for bioreactor settings.