Hydrophobicities and Electrostatic Behavior of Different Micro–organisms

Abstract: The surface properties of 7 different micro–organisms with their 14 different strains were examined. The contact angles of the micro–organism films were measured by a captive–bubble technique. Surface free energies were calculated from the contact angles. Hydrophobicities were also evaluated by adhesion to p–xylene. The zeta potentials and surface charges of the micro–organisms were measured using a zeta potential analyser system. The contact angles of the gram positive micro–organisms, gram negative micro–organisms and Candida ablicans were in the ranges 48–70°, 43.5–55°, and 69–75 ° respectively, while the corresponding surface free energies were in the ranges 44.9–60.4 erg.cm–2, 55.3–61.8 erg.cm–2 and 46.9–50.6 erg.cm–2 respectively. The p–xylene adhesions were in parallel to the hydrophobicities defined by the contat angles: 35.4–80.3%, 2.3–36.6%, and 67.3–86.2 for the gram positive bacteria, gram negative bacteria and Candida albicans yeasts respectively. The zeta potentials for these bacteria were in the ranges 14.5–650.2 mV, 6.0–159.6 mV, and 20.7–21.7 mV respectively. Most of the bacteria were negatively charged, except for the CNS–2 and CPS–1 strains