| Neonicotinoids are among the most widely used insecticides worldwide,the negative effects of them accumulated in the environment are increasing and have received widespread attention.As a new type of pollutant,the half-life of neonicotinoid insecticides varies significantly in the environment,and the microorganisms’ key role in the degradation of them is one of the main reasons for this.Microbiome has received widespread attention from scholars all over the world since it was proposed,and the soil microbiome as a crucial part of the soil environment have played a vital role in the removal of chemical pollutants.However,the research on the correlation between the soil microbiome and the degradation of neonicotinoid pesticides in soil is still very limited.In this study,the ability of microorganisms to degrade 4 neonicotinoid pesticides(imidacloprid,thiamethoxam,triflumezopyrim,and flupyradifurone)in different soil samples from different geographic fields were compared.The microbial diversity and correlation analysis of environmental factors among three groups(low,middle and high degradation group)in four pesticide treatments were performed to confirm the correlation between the degradation of neonicotinoid insecticides and soil microbiome by highthroughput sequencing,and degradation verification experiments were performed on the strains screened by correlation analysis.1)In imidacloprid treatment,α diversity indicated that the group with higher degradation rate had higher species abundance and higher diversity.At the meanwhile,βdiversity further indicated that there were significant differences in microbial composition among different groups.Based on Kruskal-wallis H test,comparative analysis of multiple groups was conducted,and found that 12 of 15 genera with the highest abundance showed significant differences among the three degradation groups.The genus with high abundance and significant difference among the three groups was selected for Ma As Lin analysis,and the screened strains were tested for degradation verification.It was found that microorganisms of Paracoccus showed no degradation activity to imidacloprid alone,but could improve the degradation rate of Achromobacter to imidacloprid.2)In thiamethoxam treatment,α diversity indicated that the group with higher degradation rate had higher species abundance.Combined with β diversity,it was found that species composition of different thiamethoxam degradation groups had significant differences.In the comparative analysis of multiple groups,among the 15 dominant genera of thiamethoxam,11 genera showed significant differences in abundance among the three groups.The selected bacteria Paracoccus and Achromobacter by Ma As Lin analysis had both certain degradation activity to thiamethoxam,but inhibition to thiamethoxam degradation was observed when the two act together.3)In triflumezopyrim treatment,α diversity showed that the higher the degradation rate of the group,the higher the species abundance and diversity.The significant differences in microbial composition of triflumezopyrim degradation groups was observed in the β diversity.A multi-group comparison of 15 dominant genera was carried out,among which the species abundance of 9 genera showed significant differences among the three groups.Ma As Lin analysis showed that uncultured microorganisms may degrade triflumezopyrim,and verification test couldn’t be conducted.4)In flupyradifurone treatment,α diversity indicated that the genus with the highest degradation rate had the lowest species abundance and diversity,and β diversity indicated that the species composition among different degradation groups varies significantly.Multi-group comparative analysis based on Kruskal-Wallis H test showed that on the species abundance,13 of the 15 dominant genera had significant differences in different degradation groups.In the verification experiment,Mizugakiibacte screened by Ma As Lin analysis did not have the ability to degrade flupyradifurone,while Chujaibacter and Acidipila both had degradation activities,and when these three genera acted together,the degradation rate of flupyradifurone was improved.This work provides novel microbial resources for the degradation of imidacloprid,thiamethoxam,and flupyradifurone,illustrates the relationship between chemical pollutant residues and soil microbiota composition,as well as expand our understanding on the dramatically change in residue period of chemical pollutants in different soils. |
