Bioremediation of fluridone by Acinetobacter bereziniae FJ-5: Metabolic pathway, metabolomics mechanism and...

Fluridone, a persistent herbicide widely utilized in cotton production, has a microbial degradation pathway that remains incompletely characterized. In this study, we isolated ten fluridone-degrading bacterial strains from cotton field soil and identified Acinetobacter bereziniae strain FJ-5 as the most efficient degrader. When cultured in mineral salt medium with 100 mg L⁻¹ fluridone as the sole carbon source, strain FJ-5 achieved 82.8 ± 0.4 % herbicide removal within 15 days. Scanning electron microscopy (SEM) imaging revealed concentration-dependent cell wall thinning, suggesting the involvement of surface-expressed proteins in the detoxification process. The degradation of fluridone by strain FJ-5 primarily proceeds through demethylation, cleavage, oxidation, hydroxylation, and carboxyl substitution reactions. Metabolic pathway analysis under fluridone stress demonstrated that fluridone is transported into the cell via membrane transport proteins for intracellular degradation. Binding of fluridone and its metabolites to the 30S ribosomal subunit activates repair mechanisms. Betaine regulates cellular osmotic pressure under fluridone stress, GABA-related pathways modulate the antioxidant system to reduce ROS generation, and the urea cycle facilitates elimination of intracellular toxic compounds. Toxicity assays confirmed that the degradation products exhibit significantly reduced toxicity compared to the parent compound. Soil microcosm phytotoxicity experiments further verified that strain FJ-5 exerts a practical and significant mitigating effect against fluridone-induced phytotoxicity. To our knowledge, this is the first experimental evidence for the potential fluridone catabolic pathway in A. bereziniae, providing a theoretical basis and technical support for bioremediation of fluridone-contaminated soils.