Hydrophobicity and biofilm formation on polystyrene by Salmonella Heidelberg isolated from a poultry slaughterhouse

Bacteria of the genus Salmonella are regarded as the major cause of food poisoning in humans, being associated with the consumption of poultry products in most countries. These bacteria can produce biofilm on different surfaces, and consequently, cleaning and sanitation procedures used in the food industry cannot remove them easily. Studies have shown that bacterial adhesion improves as hydrophobicity (both of the cell surface and of the adhesion substrate) increases. The present study assessed biofilm formation on polystyrene plates by S. Heidelberg strains isolated from poultry slaughterhouses, grown on TSB at different glucose concentrations, and the hydrophobicity of these strains in the logarithmic phase (4h) and in the stationary phase (24h) of bacterial growth. In TSB without glucose supplementation, all strains produced biofilm; two of them were strong biofilm producers, and most of them were weak biofilm producers. In TSB with 0.5, 1.0 and 1.5% dof glucose, all strains were weak biofilm producers. In TSB with 2.0 to 4.0% of glucose, several strains did not produce biofilm, whereas others were weak biofilm producers. After incubation at 36 degrees C for 4 h, the hydrophobicity index was less than 10%, and all strains were highly hydrophilic. Incubation at 36 degrees C for 24h yielded different results: 1 out of 16 strains was highly hydrophobic, 9 out of 16 were moderately hydrophobic and 6 out of 16 were highly hydrophilic. S. Heidelberg strains formed biofilm on polystyrene, which underscores the necessity to verify biofilm formation on other surfaces, in addition to investigating other hydrocarbons and incubation times in relation to hydrophobicity indices.