THE SURFACE-TENSION AND IONOGENICITY OF GIARDIA-LAMBLIA TROPHOZOITES

The surface charge of trophozoites from both P-1 and WE strains of Gia rdia lamblia was evaluated by binding cationic particles to their surf aces, and also by determinations of their electrophoretic mobilities. The presence of strongly acidic surface groups in the trophozoite was suggested by their reactivities to colloidal iron hydroxide particles (CIH). At physiological pH either P-1 or WE microorganisms had a high negative surface charge whose mean values were -2.0 and -1.4 mu m s(-1 ) V-1 cm(-1), respectively. Enzyme treatments revealed that all the su rfaces analysed possessed phospholipase C-susceptible molecules as the predominant negatively charged group. The trophozoites of G. lamblia were more adherent to hydrophobic than to hydrophilic substrates. The surface tension of G. lamblia strains P-1 and WE was 47.6 degrees and 34.8 degrees in contact angles, respectively, when the assays were car ried out with alpha-bromonaphtalene. The interfacial energy engendered in the G. lamblia-hydrophobic substrate interaction was -13.2 mJ m(-2 )for P-1 trophozoites and -18.1 mJ m(-2) for WE trophozoites.