蚯蚓对新烟碱类杀虫剂吡虫啉、啶虫脒污染红壤中细菌群落结构的影响

Effects of Earthworms on Bacterial Community Structure in Red Soil Contaminated by Neonicotinic Insecticides Imidacloprid and Acetamiprid

新烟碱类杀虫剂(neonicotinoids,NEOs)吡虫啉(imidacloprid,IMI)、啶虫脒(acetamiprid,ACE)是目前世界上使用较为广泛的杀虫剂。本研究以赤子爱胜蚓(Eiseniafoetida)为土壤动物,采用生物学模拟方法,通过高通量测序、土壤理化性质测定,分析IMI、ACE污染红壤(BCK、DCK)和引入蚯蚓后红壤(B、D)中细菌群落结构变化及其与环境因子之间的关系,探究污染红壤的动物修复机制。结果表明:与自然红壤(CK)相比,加入IMI、ACE降低了红壤的微生物丰富度和多样性,显著改变了土壤原有的细菌群落结构,使土壤有机质(SOM)和全氮(TN)含量下降;而蚯蚓的加入,增加了土壤中具有杀虫剂耐药性和降解杀虫剂能力的放线菌门(Actinobacteriota)、变形菌门(Proteobacteria)和拟杆菌门(Bacteroidota)等的相对丰度,提高了污染土壤pH、TN、全磷(TP)、全钾(TK)含量;结合土壤理化性质的相关性分析可知,在属水平上,pH、TN、TK和SOM对各处理组细菌群落结构的影响较大。研究表明,IMI、ACE污染降低了土壤TN和SOM含量,破坏了土壤中原有的细菌群落结构;蚯蚓活动提高了污染红壤的土壤肥力,缓解了IMI、ACE对土壤中微生物菌群的不利影响,在一定程度上修复和丰富了NEOs污染土壤的微生物群落物种多样性,进而加速了土壤中NEOs的降解。该研究结果为从蚯触圈中筛选出高效IMI、ACE降解菌提供可行性,可为蚯蚓对IMI、ACE污染土壤的修复提供理论基础。

Neonicotinoids(NEOs)contain imidacloprid(IMI)and acetamiprid(ACE),which are widely used in the world.In this study,earthworms(Eisenia foetida)were used as soil animal.Through high-throughput sequencing and measurement of soil physical and chemical properties,the changes of bacterial communities between IMI and ACE contaminated red soil(BCK,DCK)and soil after earthworm introduction(B,D),and the relationship with environ-mental factors were analyzed to explore the animal remediation mechanism of contaminated red soil.The introduction of IMI and ACE reduced the diversity of microbial population,significantly changed the composition of soil bacterial community structure,and decreased the content of soil organic matter(SOM)and total nitrogen(TN),compared with the natural red soil(CK).The addition of earthworms increased the relative abundance of Actinobacteriota,Proteobac-teria and Bacteroidota,which have the ability of insecticide resistance and degrading.pH value,TN,total phosphorus(TP)and total potassium(TK)contents of contaminated soil increased.Combined with the correlation analysis of soil physiochemical properties,it was found that pH,TN,TK and SOM had a great influence on the bacterial community structure among the treatment groups at the genus level.The study showed that IMI and ACE pollution reduced the contents of SOM and soil TN,and destructed the original bacterial community structure in the soil.Earthworm activity improved soil fertility of contaminated red soil,alleviated the adverse effects of IMI and ACE on soil microbial flora,restored and enriched the diversity of microbial species in NEOs-contaminated soil to a certain extent,and then acceler-ated the degradation of NEOs in soil.This study showed the feasibility to screen the efficiently IMI and ACE-degrading bacteria from drilosphere,and would provide theoretical basis for the earthworm remediation of IMI and ACE-contaminated soil.