Study on the Degradation of Residual Omethoate in Farmland Soil by Bacterial Agent PA9

【Objective】The study aims to verify the application effect of bacterial agent PA9 degrading omethoate which residual in the soil. Soil physical and chemical properties, tomato growth and soil microbial diversity affect by bacterial agent PA9 were researched at the same time.【Method】Bacterial agent PA9 was made from bacteria strain ZZY-C13-1-9, when omethoate artificial add into the soil about 100 mg/kg, the bacterial agent PA9 were applied 0.1%. The period of remediation lasted for 50 days. Soil samples were taken every 10 days. The content of omethoate in soil were measured by HPLC. A selective culture medium is used to isolate strain ZZY-C13-1-9. The microbial diversity were measured by illumina miSeq high-throughput sequencing. Soil physical and chemical indexes were determined by national standard method. Tomato growth index were monitored.【Result】Initial content of omethoate in soil was 100 mg/kg at 0 days. After 40 days, the omethoate content in soil decrease to 5.3 mg/kg at remediation experimental group, which was significantly different with control group (48.79 mg/kg). Microbial strain ZZY-C13-1-9 could colonize in the soil and the proportion of soil microorganisms in omethoate soil increased after 10 - 20 days of remediation. The residual omethoate content in the soil was significantly reduced, which indicated that the functional strain could play a role in degrading omethoate in contaminated soil. The results of high-throughput sequencing showed that the proportion of Pseudomonas sp. in soil microbial flora decreased with the decrease of omethoate content, indicating that the bacterial agent PA9 would not permanently change the distribution of soil microbial diversity, and the restored soil could effectively restore the diversity of bacterial flora. The contents of total nitrogen, microbial nitrogen, available phosphorus and MWD in soil aggregates increased significantly compared with the control, and the use of microbial agent PA9 had no negative effect on the growth of tomato.【Conclusion】The bacterial agent PA9 can colonize and accelerate the degradation of omethoate in omethoate-contaminated soil in a short period of time, improve the microbial diversity of contaminated soil and have no adverse effects on the physical and chemical properties of the soil and the planting of tomatoes.