植物影响污水处理系统重金属抗性基因分布特征研究  

Research on the distribution patterns of heavy metal resistance genes in the sewage treatment system affected by plants

作　　者：杨晶涵 余凯锋 YANG Jinghan;YU Kaifeng(Shanghai Waterway Engineering Design and Consulting Co.,Ltd.,Shanghai 200120;School of Environmental Science and Engineering,Shanghai Jiao Tong University,Shanghai 200240)

机构地区：[1]中交上海航道勘察设计研究院有限公司,上海200120 [2]上海交通大学环境科学与工程学院,上海200240

出　　处：《环境科学学报》2024年第11期155-165,共11页Acta Scientiae Circumstantiae

基　　金：国家自然科学基金(No.22206126)。

摘　　要：重金属离子对于污水处理系统中的微生物具有毒害作用,影响污水处理效能.如何提高污水处理系统的重金属耐受性是研究难点.本研究以植物耦合活性污泥系统的立体生物生态技术(处理规模25000 m^(3)·d^(-1),2015年后一直24 h稳定运行)为研究对象,通过考察污水-植物体系中13种重金属离子(砷、镉、钴、铬、铜、铁、汞、锰、镍、铅、锑、锶和锌)、9种重金属抗性基因(MRGs)和2种可移动遗传元件(intI1和tnpA6)的分布特征,探究植物影响污水处理系统重金属耐受性的机制.结果表明,该厂进水和出水中总的重金属离子浓度分别为(347.4±9.0)和(148.4±1.9)μg·L^(-1),平均去除率为57.3%,降低了污水中重金属离子的胁迫压力.通过区分污水中颗粒态(PA)和浮游态(FL)微生物,发现FL态MRGs的种类和相对丰度要高于PA态.而4种植物根际中MRGs的检出数量和相对丰度均较污水低.结构方程模型(SEM)表明,影响污水中MRGs丰度变化的因素排序为:微生物多样性>微生物形态>可移动遗传元件>重金属离子.总之,引入植物可以改变污水处理系统中PA和FL态微生物群落结构,并通过根系分泌物以及与根际微生物的协同作用等途径,提高污水处理系统的重金属耐受性.本研究可为污水处理系统通过生态方法应对重金属胁迫提供科学参考.Heavy metal ions exhibit toxic effects on microorganisms within sewage treatment systems,thereby reducing sewage treatment efficiency.Improving the heavy metal tolerance of sewage treatment systems is a significant research challenge.This study investigated the tridimensional ecobiological technology that integrates activated sludge and plants(with a treatment capacity of 25000 m^(3)·d^(-1),operating stably 24 hours a day since 2015)to explore how plants affect heavy metal tolerance in sewage treatment systems.The distribution patterns of 13 types of heavy metal ions(As,Cd,Co,Cr,Cu,Fe,Hg,Mn,Ni,Pb,Sb,Sr and Zn),9 heavy metal resistance genes(MRGs)and 2 mobile genetic elements(intI1 and tnpA6)in the wastewater-plants system were profiled.Results showed that the total concentrations of heavy metal ions in the influent and effluent were(347.4±9.0)and(148.4±1.9)μg·L^(-1),respectively,with an average removal efficiency of 57.3%,thereby reducing the stress exerted by heavy metal ions in the sewage.By distinguishing between particle-associated(PA)and free-living(FL)microorganisms,it was found that the FL-MRGs subtypes and relative abundances were higher than those of PA fractions.Additionally,MRG counts and relative abundances in the rhizospheres were lower than in the sewage.A structural equation model(SEM)showed that the factors influencing the relative abundance dynamics of MRGs in the sewage ranked as follows:microbial diversity>microbial morphology>mobile genetic elements>heavy metal ions.In summary,plants alter the structures of PA-and FL-microbial communities in the sewage treatment system,and enhance the heavy metal tolerance through root exudates and synergistic interactions with rhizosphere microorganisms.This study provides scientific insights for using ecological methods to address heavy metal stress in sewage treatment systems.

关 键 词：重金属 重金属抗性基因 活性污泥-植物体系 根际 微生物群落 

分 类 号：X171.5[环境科学与工程—环境科学]