Accelerated elimination of enrofloxacin and improvement of Cyprinus carpio health via Lactiplantibacillus plantarum YZ2 triggered NRF2 activation

Antibiotic residues in aquatic environments and products pose significant threats to both water security and human health. Enrofloxacin (EFX), a widely used fluoroquinolone, is of particular concern due to its persistence and potential for resistance dissemination. This study investigated the efficacy and underlying mechanism of Lactiplantibacillus plantarum YZ2 immersion in accelerating EFX clearance and enhancing flesh quality in Cyprinus carpio . Following a 5-day EFX enrichment phase, carp (50.01 ± 1.12 g) were subjected to 14 days of YZ2 immersion (1 × 10 6 CFU/mL). Results demonstrated that natural recovery was insufficient for EFX clearance within 14 days; however, YZ2 immersion significantly accelerated elimination, reducing hepatic and muscular residues by 42.94% and 56.99% at Day 7, respectively ( P < 0.05). Notably, a transient spike in muscular EFX at Day 3 mirrored hepatic overload and passive redistribution, a process subsequently resolved by a YZ2-triggered detoxification burst. Mechanistically, YZ2 orchestrated the NRF2 signaling pathway, co-ordinately upregulating Phase I/II detoxification enzymes (e.g., CYP3A4, UGT-2B7) and ABC transporters (e.g., Mrp-3 , P-gp ). Bidirectional validation using NRF2 modulators confirmed that NRF2 activation enhanced EFX metabolic flux and environmental excretion, while its inhibition exacerbated tissue accumulation. Furthermore, YZ2 immersion significantly improved flesh quality by stimulating myofiber hyperplasia and collagen synthesis via the upregulation of Myod, Myog , and Col1a1/a2 genes ( P < 0.05). These findings suggest that YZ2 immersion provides a scalable and eco-friendly bioremediation strategy to mitigate antibiotic contamination in aquaculture, ensuring both food safety and biological security.