Biodegradation of acetochlor by microbial consortium AT1: microcosm centric microbiomic-metabolomics mechanisms and environmental remediation feasibility

Abstract

The excessive use of herbicide acetochlor (ACT) threatens crop health and the environment, necessitating effective remediation strategies. This study focused on a consortium named AT1, enriched from ACT-contaminated soil. Under optimized conditions (25 °C, pH 7, 1 % inoculum), AT1 almost completely degraded ACT (50–1000 mg/L) within 6–12 days. High-throughput sequencing of 16S rRNA gene revealed a reduction in community diversity over time, with Sphingomonas (58.6 %) and Diaphorobacter (26.43 %) as dominant taxa. A structure model and network analysis indicated strong microbial competition during the peak degradation. Predicted functions and liquid chromatography-mass spectrometry based metabolomics data identified benzene ring intermediates during ACT degradation, including 2,6-dimethylaniline, resorcinol, phenol, 3-ethyl-1,2-benzenediol, 1,2,3-trihydroxybenzene, phloroglucinol, and benzene-1,2,4-triol. Joint omics analysis revealed that AT1 likely degrades ACT via N-dealkylation by Pseudomonas, amide bond hydrolysis by Diaphorobacter, and carboxylation and hydroxylation by Sphingomonas, leading to the formation of these intermediate metabolites. Moreover, AT1 efficiently degraded key intermediates, particularly 2,6-dimethylaniline, phenol, and resorcinol, further enhancing ACT mineralization. Notably, AT1 efficiently degraded ACT in soil, resulting in a significant decrease in ACT environmental residues. These findings provide valuable insights for the discovery and identification of herbicide-degrading bacterial resources and the metabolic transformation of herbicides, and developing approaches for pollution control and biodegradation of amide herbicides.