Antimicrobial Efficacy of Quercetin against Vibrio parahaemolyticus Biofilm on Food Surfaces and Downregulation of Virulence Genes

For the seafood industry, Vibrio parahaemolyticus, one of the most prevalent food-borne pathogenic bacteria that forms biofilms, is a constant cause of concern. There are numerous techniques used throughout the food supply chain to manage biofilms, but none are entirely effective. Through assessing its antioxidant and antibacterial properties, quercetin will be evaluated for its ability to prevent the growth of V. parahaemolyticus biofilm on shrimp and crab shell surfaces. With a minimum inhibitory concentration (MIC) of 220 µg/mL, the tested quercetin exhibited the lowest bactericidal action without visible growth of bacteria. In contrast, during various experiments in this work, the inhibitory efficacy of quercetin without (control) and with sub-MICs levels (1/2, 1/4, and 1/8 MIC) against V. parahaemolyticus was examined. With increasing quercetin concentration, swarming and swimming motility, biofilm formation, and expression levels of related genes linked to flagella motility (flaA and flgL), biofilm formation (vp0952 and vp0962), and quorum-sensing (luxS and aphA) were all dramatically reduced (p < 0.05). Quercetin (0−110 μg/mL) was investigated on shrimp and crab shell surfaces, the inhibitory effects were 0.68−3.70 and 0.74−3.09 log CFU/cm2, respectively (p < 0.05). The findings were verified using field emission scanning electron microscopy (FE-SEM), which revealed quercetin prevented the development of biofilms by severing cell-to-cell contacts and induced cell lysis, which resulted in the loss of normal cell shape. Furthermore, there was a substantial difference in motility between the treatment and control groups (swimming and swarming). According to our findings, plant-derived quercetin should be used as an antimicrobial agent in the food industry to inhibit the establishment of V. parahaemolyticus biofilms. These findings suggest that bacterial targets are of interest for biofilm reduction with alternative natural food agents in the seafood sector along the entire food production chain.