Green manure plant and exogenous degrading bacteria synergistically promote atrazine removal by enriching indigenous rhizosphere degraders

Abstract

Atrazine, a persistent triazine herbicide, poses environmental and health risks. This study examines the synergistic remediation of atrazine-contaminated soil using green manure plant (GMP) hairy vetch (Vicia villosa Roth, VV) and the exogenous atrazine-degrading bacterium Arthrobacter sp. ATR1. Soil samples contaminated with atrazine at 5 and 20 mg/kg were treated with control (CK), ATR1 (CKatr), hairy vetch (VV), and combined hairy vetch and ATR1 remediation (VVatr). The results indicated that the VVatr treatment exhibited the most effective atrazine removal, achieving enhancements of 56.12 % at 5 mg/kg and 54.51 % at 20 mg/kg compared to CK after 28 days. Soil enzyme activities, including urease, sucrase, and alkaline phosphatase, were significantly elevated in the VV and VVatr treatments, contributing to improved soil quality. Additionally, the CKatr, VV, and VVatr treatments enhanced bacterial diversity and richness while altering the microbial community structure. The VV and VVatr treatments notably enriched indigenous atrazine-degrading bacteria and nitrogen-fixing bacteria in the rhizosphere. This microbial enrichment upregulated the Atrazine degradation and Nitrogen metabolism pathways, facilitating both atrazine removal and nitrogen cycling in the soil. And VVatr treatment promoted the stability of the microbial network and enhanced the cooperative relationship between key indigenous atrazine-degrading and nitrogen-fixing bacteria. These findings explain the mechanism of plant-microbe combined remediation of atrazine-contaminated soil from the perspective of rhizosphere microorganisms and offer a theoretical basis for the practical application of this method.