# The Remediation Mechanism of Soil Atrazine Contamination by Vermicompost: A Metagenomic Perspective

## TL;DR

This study explores how vermicompost helps break down atrazine in soil by analyzing microbial communities and key genes involved in the process.

## Contribution

The study identifies specific microbial genera and functional genes enriched by vermicompost that enhance atrazine degradation.

## Key findings

- Vermicompost significantly restructured soil microbial communities, increasing Proteobacteria and Bacteroidetes abundance.
- SnV2 showed the highest atrazine degradation (2.94%) and enriched Bauldia for dechlorination.
- 60-day vermicompost (SnV2) upregulated key genes like trzN and atzB, demonstrating superior remediation performance.

## Abstract

Atrazine persistence poses serious environmental threats. This study used metagenomics and qPCR to elucidate the remediation mechanism of vermicompost in atrazine degradation pathways. Seven treatments were established: unsterilized soil (CKn); sterilized soil amended with 45 (SsV1), 60 (SsV2), and 75 (SsV3) days of vermicompost; and unsterilized soil with the same vermicompost (SnV1, SnV2 and SnV3). Vermicompost significantly restructured soil microbial communities. SsV1 exhibited the highest Proteobacteria abundance (51.38%), while SsV3 markedly increased Bacteroidetes abundance (10.34%). Functional annotation revealed that vermicompost enriched carbohydrate metabolism-related COG units and upregulated CAZymes (e.g., CE1 and CE10 families), providing energy support for degrading microbial communities. Regarding metabolic pathways, SnV2 exhibited the highest atrazine degradation abundance (2.94%), significantly enriching Bauldia (4.84 RPKM) for dechlorination. During cyanuric acid ring-opening, SnV3 significantly enriched Pseudorhodoplanes (12.14 RPKM). During terminal mineralization, SsV2 increased Caenimonas abundance (15.25 RPKM) and introduced the exogenous genus Pseudorhodoplanes (7.78 RPKM). qPCR confirmed SnV2’s trzN (day 20) and atzB (day 40) reached 9.03 × 104 and 6.95 × 107 copies/g, respectively. These findings indicate vermicompost accelerated atrazine mineralization by enriching degradative microbial communities and promoting key functional gene expression, with 60-day vermicompost demonstrating superior performance. This study provides a robust theoretical framework for remediating atrazine-contaminated soil by vermicompost.