Enrichment, domestication, degradation, adaptive mechanism, and nicosulfuron bioremediation of bacteria consortium YM2

Nicosulfuron (NSR), a sulfonylurea herbicide, readily infiltrates water bodies, potentially compromising aquatic ecosystems and human health. In this study, bacteria consortium YM2 was isolated and cultivated from pesticide plant active sludge for NSR wastewater bioremediation. Response surface methodology analysis demonstrated that under optimal cultivation conditions (9.41 g L^–1 maltodextrin, 21.37 g L^–1 yeast extract, and 12.45 g L^–1 NaCl), the YM2 bacteria consortium achieved 97.49% NSR degradation within 4 d. Optimal degradation parameters were established at 30°C, pH 6.0, 1% inoculum, and 20 mg L^–1 initial NSR concentration. The degradation system demonstrated resistance to heavy metal ions including Cd²⁺, Pb²⁺, Ni²⁺, and Zn²⁺, with degradation primarily occurring through bacterial extracellular enzymes (92.17%). During the degradation process, reactive oxygen species, oxidative stress, cell membrane permeability, cell surface hydrophobicity, and apoptosis rate exhibited initial increases followed by decreases. Additionally, biofilm formation-related genes luxS, waaE, spo0A, and wza showed temporal and concentration-dependent expression patterns. NSR concentrations in wastewater and soil were reduced to 1.92 and 2.72 mg L^–1, respectively. In a simulated wastewater treatment unit with a 12-h hydraulic retention time, YM2 achieved 84.55% NSR degradation after 10 d. These findings provide a theoretical foundation for microbial remediation of NSR contamination.