Evaluation of the antibacterial mechanism and biofilm removal effect of eugenol on Vibrio vulnificus and its application in fresh oysters

Abstract

Eugenol is a natural active substance with high antibacterial activity, but its antibacterial activity against Vibrio vulnificus has not been extensively studied. The purpose of this study was to investigate the antibacterial and biofilm-clearing abilities and potential mechanisms of eugenol against V. vulnificus, and to provide knowledge for the use of eugenol to prevent oyster contamination. It was found that eugenol had an encouraging antibacterial effect on V. vulnificus with a minimum inhibitory concentration (MIC) of 0.2 mg/mL. The accumulation of reactive oxygen species (ROS) and the increase of malondialdehyde (MDA) content suggest that oxidative stress is involved in the bactericidal mechanism. Moreover, cell membrane hyperpolarization, changes in cell membrane integrity and morphology suggest that eugenol can reduce the permeability and integrity of cell membranes in V. vulnificus. In addition, eugenol produced a significant biofilm clearance effect on V. vulnificus, as evidenced by the reduced amount of biofilm and the reduction of polysaccharides and viable cells in the biofilm. Finally, eugenol was able to effectively inhibit the activity of V. vulnificus in artificially contaminated oyster at 4 °C and 25 °C. But sensory analysis showed that 0.10% eugenol was most acceptable to trained panelists. All of these highlight the great promise of eugenol as a natural bacteriostatic agent for the food industry.