Antibacterial Effects of Magnolol and Palmatine on Three Common Pathogenic Bacteria in Fish

We used double dilution method and filter paper method, selected two kinds of plant extracts that were magnolol, palmatine, made up six kinds of different concentration respectively with the selected plant extracts.The three common aquatic pathogens were Aeromonas hydrophila, Aeromonas sobria and Vibrio parahaemolyticus in this study. The aim was to find out the inhibitory effects of three plant extracts on the three common aquatic pathogens. The results suggested that magnolol and palmatine could inhibit the growth of A.hydrophila and V.parahaemolyticus obviously(P0.05), when the concentration of magnolol was 3.125 mg/mL, the inhibitory zones diameter of A.hydrophila and V.parahaemolyticus were (15.130.29) mm,(15.700.34) mm,respectively and with high sensitivity. The inhibitory zones diameter of A.hydrophila and V.parahaemolyticus decreased gradually as the concentration of Palmatine decreased. However, magnolol and palmatine had no inhibition effect on the Aeromonas sobria(P0.05).