Structural interactions and transcriptional regulation by caffeic acid against multidrug-resistant Vibrio species: Mechanistic insights and efficacy in shrimp.

This study aimed to investigate antimicrobial effects of caffeic acid (CA) against multidrug-resistant Vibrio parahaemolyticus and Vibrio cholerae both in vitro and in shrimp (Penaeus vannamei). CA at concentrations of 0.47-0.94 mg/mL disrupted bacterial membrane integrity, resulting in increased nucleic acid leakage and decreased intracellular DNA content. At 1 × minimum inhibitory concentration (MIC), CA inhibited biofilm formation, with maximum reductions of 76.4 % and 68.3 % for V. parahaemolyticus and V. cholerae, respectively. Molecular dynamics simulations revealed stable binding between CA and critical bacterial proteins except for ompW, with binding energies of -6.6 to -5.8 kcal/mol. RT-qPCR further confirmed downregulation of related gene expression. In shrimp, CA treatment (6 × MIC, 4 h) reduced both Vibrio species by >4.4 log CFU/g. These results demonstrate the potent anti-Vibrio activity of CA, underscoring its potential as a plant-derived antimicrobial agent for ensuring microbial safety in seafood processing industry.