Metabolite identification of alpha-cypermethrin biodegradation by citrus bacteria.

Alpha-cypermethrin is a type II pyrethroid insecticide widely used in agriculture, including for citrus production, but its persistence and toxicity to non-target organisms raise environmental and health concerns. In this study, citrus-associated bacteria were evaluated for the biodegradation of (±)-alpha-cypermethrin, with emphasis on metabolite identification and pathway elucidation. Priestia megaterium CBMAI 2842 isolated from orange leaves, were cultivated in liquid medium containing 100 mg L⁻¹ of commercial (±)-alpha-cypermethrin and incubated at 32 °C and 130 rpm for 5 days. Metabolites were investigated by GC–MS and LC–MS/MS-based untargeted metabolomics. LC-MS/MS-based revealed a clear metabolic differentiation between biodegradation samples and control groups, supporting the formation of biodegradation-related features and confirming that α-cypermethrin transformation by P. megaterium CBMAI 2842 induces a distinct metabolic profile. The tentatively identified compounds by LC-MS/MS were 3-phenoxybenzoic acid, hydroxy-3-phenoxybenzoic acid, permethrinic acid, 3-phenoxybenzamide, a ketone derivative and 3-phenoxybenzaldehyde. GC–MS analysis enabled the tentatively identification of ten metabolites associated with alpha-cypermethrin transformation. The detected metabolites suggest that biodegradation occurs mainly through ester bond hydrolysis, followed by oxidation, reduction, ether bond cleavage, and formation of lower-molecular-weight aromatic compounds. These findings indicate that P. megaterium CBMAI 2842 is an efficient citrus-associated biocatalyst for alpha-cypermethrin transformation and may contribute to future bioremediation strategies for pyrethroid-contaminated environments.