Abstract: The inhibitory effect of garlic extract on biofilm development in Pseudomonas fluorescens was studied. The biofilm produced by the bacteria was determined using crystal violet staining and light microscope, phenol sulfuric acid method was used to test the production of extracellular polysaccharides, the synergistic effect of garlic extract with potassium sorbate was studied by porous plate method. The results showed that the inhibitory rates of garlic extract on biofilm development were 27.6% and 38.7%, the inhibitory rates on extracellular polysaccharide were 4.5% and 12.6%, respectively, at the concentration of the garlic extract 100 mg/mL and 150 mg/mL, garlic extract showed synergistic effect with potassium sorbate at the concentration of 100 mg/mL. Therefore, garlic extract inhibited the biofilm formation in P. fluorescens.

Key words: Pseudomonas fluorescens, biofilm, garlic extract