Purpose: The aim of this study was to evaluate the effects of blueberries on the biofilm formation of V. parahaemolyticus.
Methods: Wild blueberries (Vaccinium angustifolium and Vaccinium uliginosum) and cultivar blueberries (DingFeng) were chosen for this study. V. parahaemolyticus strains ATCC33847, ATCC17802 and O3:K6 were selected. Crystal violet staining assay was used to measure the biofilm production of V. parahaemolyticus in different time periods. Planktonic susceptibility and biofilm susceptibility were measured under different concentrations of blueberry crude extract treatment. Susceptibilities were determined by minimum inhibitory concentrations (MICs), minimum bactericidal concentrations (MBCs), minimum biofilm inhibitory concentrations (MBICs) and minimum biofilm bactericidal concentrations (MBBCs), and the plate count method. Fluorescence microscope was also used to observe the effects of blueberry on biofilm formation in 24 h, 48 h, 72 h and 96 h, compared with the control group (without blueberry).
Results: The results showed that the most biofilm production of V. parahaemolyticus resulted from incubation of 30 h. The MICs and MBICs were 15.625 mg/ml and 31.25 mg/ml, respectively. The MBCs and MBBCs were 62.5 mg/ml and 125 mg/ml, respectively. These results indicated that biofilms were more resistant to the blueberry treatments when compared to the bacterial cells. Through fluorescence microscope, we found the biofilm formation was reduced by blueberry treatments when compared with no blueberry controls.
Significance: This study suggests that blueberries may reduce the biofilm formation of V. parahaemolyticus, indicating they have the capability to detach and kill existing biofilms. The results of this study lay the foundation for future characteristics and mechanism research.