Effect of R-plasmid RP1 on surface hydrophobicity of Proteus mirabilis.

The presence of R-plasmid RP1, as well as the conditions of growth, affected the surface hydrophobicity of a clinical isolate of Proteus mirabilis. However, results depended upon the method of assessment. Stationary phase plasmid-containing cells appeared to be less hydrophobic than plasmid-free cells when hydrophobicity was measured by the contact angle method, but more hydrophobic when measured by bacterial adherence to hydrocarbons or hydrophobic interaction chromatography. Cells growing in a chemostat differed in hydrophobicity from stationary phase cells and results varied with the growth rate. Plasmid-mediated effects were greatest in iron-depleted cells, and differences between plasmid-containing and plasmid-free cells were virtually eliminated by pre-treatment with antiserum.