Integrated nanoemulsion based functional feed against Vibrio parahaemolyticus pathogenesis in Penaeus vannamei: physicochemical characterization and in vivo efficacy.

The global production of Penaeus vannamei shrimp is threatened by Vibrio parahaemolyticus, a pathogen causing severe disease outbreaks and economic losses, especially in Asia. This study developed and characterized stable sunflower oil-based nanoemulsions (NEs) and incorporated them into formulated feed for targeted antimicrobial control. Physicochemical analyses (particle size, zeta potential, viscosity, stability) confirmed uniform formulations. Antimicrobial efficacy was evaluated using MIC/MBC, adherence, biofilm inhibition, oxygen consumption rate (OCR), and virulence gene expression assays. NE-23 and NE-27 showed strong antibacterial activity (MIC/MBC: 1-256/2-170 µg/mL), consistent with gentamicin. NE-22 exhibited the highest anti-adherence activity (70.62%), while NE-23 and NE-21 were most effective against pathogenic strains. Biofilm inhibition reached 72.17% (NE-22, MTCC-451) and 59-60% (NE-23, shrimp isolates), comparable to gentamicin. Dead cell assays revealed NE-24 induced up to 68.52% mortality, surpassing gentamicin in some strains. OCR analysis showed greater inhibition by NE-22 (0.31-fold reduction) than gentamicin (0.66-fold). Gene expression profiling demonstrated relative downregulation by NE-23. Finally, nanoemulsion-infused formulated feed conferred in vivo protection against V. parahaemolyticus without affecting shrimp growth or survival. Overall, NE-22 and NE-23 emerged as potent antibiotic alternatives, offering a sustainable strategy to mitigate V. parahaemolyticus infections in shrimp aquaculture.