Lactiplantibacillus plantarum YZ2 immersion reduces chloramphenicol residues in common carp (Cyprinus carpio).

BACKGROUND: The antibiotic toxicity and risks associated with their residues pose a serious threat to food safety. OBJECTIVE: The aim of this study is to investigate the mechanism by which probiotic immersion reduces antibiotic residues in common carp. METHODS: A chloramphenicol (CAP) enrichment model was established in common carp (Cyprinus carpio), followed by screening for CAP-depleting strains from six candidate Lactobacillus strains. A total of 270 Carp (50.01±1.12 g) were then immersed with screened strains for 14 days. CAP residues in tissues and water were monitored using High-Performance Liquid Chromatography (HPLC). Hepatic Phase I/II enzymes, ATP-binding cassette (ABC) transporters, antioxidant enzymes and cytokines were analyzed via enzyme-linked immunosorbent assay (ELISA) and reverse transcription quantitative real-time PCR (RT-qPCR). The involvement of the nuclear factor erythroid 2-related factor 2 (NRF2) signaling pathway in CAP elimination and flesh quality improvement was further validated using the NRF2 activator sulforaphane and the inhibitor VVD-130037. Data were subjected to one-way analysis of variance (ANOVA) or Student's t-test to determine statistical significance. RESULTS: Natural recovery failed to clear CAP residues within 14 days. In contrast, Lactiplantibacillus plantarum YZ2 immersion significantly accelerated CAP elimination, reducing hepatic and muscular residues by 42% and 38% at day 7, respectively (P<0.05). Mechanistically, YZ2 activated the hepatic NRF2 signaling pathway, which coordinately upregulated Phase I/II enzymes (e.g., cytochrome P450 (CYP) 3A-like, UDP-glucuronosyltransferase [UGT]-family) and ABC transporters (e.g., abcb3, abcb4), enhancing systemic excretion. Pharmacological activation of NRF2 mimicked YZ2's effects, reducing residues (P<0.01) and mitigating oxidative stress (total antioxidant capacity [T-AOC] increased by 35%, P<0.05), while NRF2 inhibition abrogated these protective benefits. Furthermore, YZ2 enhanced flesh quality by upregulating myogenic regulatory factors (myf5, myod1, myog) and collagen genes (col1a1a, col1a2) (P<0.05), leading to a 22% increase in myofiber density. CONCLUSIONS: These findings demonstrate that L. plantarum YZ2 facilitates antibiotic depletion and improves muscle quality through an NRF2-mediated hepatic biotransformation and tissue-specific clearance.