Inhibitory Effect of Quercetin on Biofilm Formation of Salmonella
[Objective]The objective of this experiment was to study the inhibitory effect of quercetin on the biofilm formation of Salmonella and its mechanism.[Method]The growth curve of Salmonella biofilms was plotted by crystal violet staining,and the minimum biofilm inhibitory concentration(MBIC)of quercetin on Salmonella was determined.The bacteria were treated with quercetin,and the metabolic activity and morphology of the bacteria in Salmonella biofilms were observed by XTT method and scanning electron microscope.The contents of exopoly saccharides,protein and DNA of Salmonella biofilm were detected by phenol-sulfuric acid method,BCA method and ultraviolet spectrophotometer,respectively.The hydrophobicity and motility of Salmonella were determined by bacteria adhesion to hydrocarbons and soft agar method.[Result]The results of growth curve showed that the adhesion,aggregation,maturation and dispersion periods of Salmonella biofilms were 0-48,48-72,72-120 and 120-168 h,respectively.The MBIC of quercetin against Salmonella biofilms was 256 μg/mL.The metabolic activity of bacteria in Salmonella biofilm treated with quercetin was extremely significantly decreased at different times(P＜0.01).Scanning electron microscopy observation showed that after quercetin treatment,the structure of Salmonella biofilms was destroyed and the membrane-like substance disappeared.Compared with control group,the exopoly saccharides,protein and DNA contents of Salmonella biofilms in quercetin group were extremely significantly decreased(P＜0.01).The hydrophobicity index,swimming motility diameter and swarming motility diameter of Salmonella decreased extremely significantly(P＜0.01).[Conclusion]Quercetin inhibited biofilm formation by affecting the metabolic activity of bacteria in Salmonella,reducing the production of extracellular polymeric substances,and interfering with surface hydrophobicity and motility of Salmonella.
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