Antibacterial effect of phenyllactic acid against Vibrio parahaemolyticus and its application on raw salmon fillets

The antibacterial effects of phenyllactic acid (PLA) against Vibrio parahaemolyticus and its application on raw salmon fillets (RSF) were investigated in this study. The minimum inhibitory concentration (MIC) of PLA against V. parahaemolyticus was 3.2 mg/mL. Interestingly, PLA at sub-MIC (0.4 mg/mL) completely inactivated planktonic V. parahaemolyticus under saline condition. The influence of PLA on bacterial membrane and genomic DNA was explored to reveal its antibacterial mechanism. Although no obvious morphological changes were observed by scanning electron microscope, the permeability of bacterial membrane was increased and the leakage of potassium was detected under PLA stress. DNA interaction analysis illustrated that PLA was intercalative with genomic DNA, which might influence normal physiological functions of bacteria. Besides, PLA at sub-MIC could effectively inhibit the motility (i.e., swimming and swarming) of V. parahaemolyticus, thereby inhibiting its biofilm formation. The in vivo antibacterial tests confirmed that PLA at 8 MIC was capable of eliminating the contamination of V. parahaemolyticus on RSF thoroughly, while low concentration of PLA could also be used as an antibacterial agent to inhibit the growth of V. parahaemolyticus on RSF, suggesting that PLA was a promising candidate for the control of foodborne pathogens in chilled aquatic products.