Biodegradation mechanism of butralin by a newly isolated <i>Bacillus velezensis</i> FC02

Butralin is a selective pre-budding agent. It is relatively immobile in the substrate after application, and its transmission through the food chain poses a potential threat to human health. In this study, we isolated a butralin-degrading strain FC02, and identified it as <i>Bacillus velezensis</i>. Optimization of butralin degradation with Box-Behnken design resulted in 89.12% degradation at pH 8.4, OD₆₀₀ = 2.5, 35.0 °C, and 200 mg FC02. Strain FC02 efficiently converted butralin into five products through nitro-reduction, dealkylation, and hydroxylation reactions, differing from the mechanisms and pathways in other strains. Genomics and transcriptomic analyses revealed that nitroreductase genes are involved in the nitro-reduction process of butralin degradation. Here, we explored the degradation characteristics and metabolic pathways of strain FC02, providing an in-depth understanding of the mechanism of microbiological degradation of butralin.