Cell surface properties and biofilm formation of pathogenic bacteria

Cell surface properties of slime production, cell hydrophobicity (CH), colony spreading, auto-aggregation, and biofilm formation (BF) of pathogens were investigated. Staphylococcus aureus, Pseudomonas aeruginosa, and Listeria monocytogenes generally formed strong biofilms and were positive slime producers. The extracellular polymeric substances isolated from agar-grown biofilms of Bacillus cereus and P. aeruginosa contained a high proportion of carbohydrates, proteins, and extracellular DNA. High levels of CH were observed for all pathogens when hydrocarbons were combined with ammonium sulfate (AS). Levels of hydrophobicity based on bacterial adhesion to hydrocarbons using nonane with AS were positively correlated with hydrophobic interaction chromatography assay and contact-angle measurement results. BF and CH values of all pathogens, except E. coli O157:H7 and B. cereus, were highly correlated. Levels of pathogen hydrophobicity differed depending on the measurement method. Factors affecting BF were different depending upon the pathogen.