Hydrophobicities and Electrostatic Behavior of Different Micro-organisms

Authors : Abbas Yousefi RAD

Pages : 215-232

View : 22 | Download : 9

Publication Date : 2000-12-01

Article Type : Research Paper

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.
Keywords : Micro organisms, hydrophobicity, contact angle, surface free energy, p xylene adhesion, zeta potential, surface charge