CHARACTERISTICS OF BIOFILM FORMATION BY SELECTED FOODBORNE PATHOGENS

초록

Strains of Listeria monocytogenes, Serratia liquefaciens, Shigella boydii, Staphylococcus aureus, Salmonella Enteritidis, and Bacillus cereus were used to evaluate bacterial biofilm-forming ability in trypticase soy broth (TSB; pH 6 and pH 7) at 37C. The biofilm development was determined by using the crystal violet method and the degree of biofilm formation was expressed as the specific biofilm formation (SBF) index. Among all strains tested, L. monocytogenes and S. liquefaciens formed strong biofilms in half-strength TSB (pH 6), showing 2.79 and 3.85 of SBF indices, respectively. The numbers of adhered L. monocytogenes and S. liquefaciens increased to 7.57 and 7.91 cfu/slide, respectively, after 36 h. The increase in the biofilm formation of L. monocytogenes and S. liquefaciens was shown in the scanning electron microscopy micrographs. The protein profile differences were observed between biofilms and planktonic cells, suggesting that biofilm-specific protein expression is involved in the biofilm development.

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