Understanding the Degradation and Stress Response Mechanisms of Cypermethrin by <i>Bacillus subtilis</i> J6 Isolated from Broiler Gastrointestinal Tract

Pyrethroid residues in the environment and agricultural products have caused significant negative effects on food safety and human health. In this study, a novel strain of <i>Bacillus subtilis</i> J6, isolated from the cecum of broilers, exhibited the ability to degrade cypermethrin and its major metabolite, 3-phenoxybenzoic acid. The identified intermediates indicated that <i>B. subtilis</i> J6 degrades cypermethrin through ester bond hydrolysis, benzene hydroxylation, and ether bond cleavage. Predictive toxicology analysis suggested that this degradation process effectively reduces toxicity. Transcriptomic analysis revealed that esterases, oxidoreductases, cytochrome P450 enzymes, and ring-cleavage dioxygenases may contribute to cypermethrin degradation. In addition, <i>B. subtilis</i> J6 mitigates cypermethrin stress by enhancing growth metabolism, sporulation, and material transport, whereas it downregulates pathways associated with cell motility and respiration. These findings identify <i>B. subtilis</i> J6 as a promising candidate for pyrethroid bioremediation in the food and feed industries and provide new insights into its degradation pathways and adaptive responses.