Habash Marc B, van der Mei Henny C, Reid Gregor, Busscher Henk J
Department of Microbiology and Immunology, University of Western Ontario Health Sciences Centre, London, Ontario, Canada N6A 5C1.
Materia Technica, University of Groningen, Bloemsingel 10, 9712 KZ Groningen, The Netherlands.
Microbiology (Reading). 1997 Aug;143 ( Pt 8):2569-2574. doi: 10.1099/00221287-143-8-2569.
The physico-chemical cell-surface properties of Pseudomonas aeruginosa AK1 and its adhesion to silicone rubber under flow were compared for cells suspended in phosphate-buffered saline (PBS) or PBS supplemented with 2% nutrient broth. Addition of 2% nutrient broth to cells suspended in PBS yielded minimal growth and did not significantly change the mean zeta potential of the organisms, which was around -13 mV. However, a comparatively larger proportion of the organisms had more negative zeta potentials in the presence of nutrient broth. This change was concurrent with a slight decrease in cell-surface hydrophobicity, as measured by water contact angles, from 119 degrees to around 112 degrees. The initial deposition rate of P. aeruginosa AK1 to silicone rubber, as studied in a parallel plate flow chamber, increased from 344 cm-2 s-1 in the absence of nutrient broth to 505 cm-2 s-1 in its presence. No stationary level of adhesion was observed in the presence of nutrient broth, instead the number of adhering cells increased steadily at a rate of approximately 85 cm-2 s-1. Fluorescent staining of adhering cells demonstrated that for adhesion from buffer only 2% of the adhering cells were metabolically active, whereas in case of deposition from PBS supplemented with nutrient broth, 67% of the adhering cells were metabolically active. It is concluded that the deposition rates measured in the parallel plate flow chamber with 2% nutrient broth added to the PBS suspension represent an interplay of adhesion and surface-associated growth.
