Antibacterial and anti-virulence potential of plant phenolic compounds against Vibrio parahaemolyticus [version 2; peer review: 2 approved with reservations]

Background: Vibrio parahaemolyticus is a pathogenic bacterium that affects shrimp aquaculture; its infection can lead to severe production losses of up to 90%. On the other hand, plant phenolic compounds have emerged as a promising alternative to combat bacterial infections. The antibacterial and anti-virulence activity of the plant phenolic compounds quercetin, morin, vanillic acid, and protocatechuic acid against two strains of V. parahaemolyticus (Vp124 and Vp320) was evaluated. Methods: The broth microdilution test was carried out to determine phenolic compounds' antibacterial activity. Moreover, the biofilm-forming ability of V. parahaemolyticus strains in the presence of phenolic compounds was determined by total biomass staining assay using the cationic dye crystal violet. The semisolid agar displacement technique was used to observe the effect of phenolic compounds on the swimming-like motility of V. parahaemolyticus. Results: Results showed that phenolic compounds inhibited both strains effectively, with minimum inhibitory concentrations (MICs) ranging from 0.8 to 35.03 mM. Furthermore, at 0.125 - 0.5 × MIC of phenolic compounds, V. parahaemolyticus biofilms biomass was reduced by 63.22 - 92.68%. Also, quercetin and morin inhibited the motility of both strains by 15.86 - 23.64% (Vp124) and 24.28 - 40.71% (Vp320). Conclusions: The results suggest that quercetin, morin, vanillic, and protocatechuic acids may be potential agents for controlling V. parahaemolyticus.