C. Drozd et J. Schwartzbrod, HYDROPHOBIC AND ELECTROSTATIC CELL-SURFACE PROPERTIES OF CRYPTOSPORIDIUM-PARVUM, Applied and environmental microbiology, 62(4), 1996, pp. 1227-1232
Microbial adhesion to hydrocarbons and microelectrophoresis were inves
tigated in order to characterize the surface properties of Cryptospori
dium parvum, Oocysts exhibited low removal rates by octane (only 20% o
n average), suggesting that the Cryptosporidium sp. does not demonstra
te marked hydrophobic properties, A zeta potential close to -25 mV at
pH 6 to 6.5 in deionized water was observed for the parasite, Measurem
ents of hydrophobicity and zeta potential were performed as a function
of pH and ionic strength or conductivity, Hydrophobicity maxima were
observed at extreme pH values, with 40% of adhesion of oocysts to octa
ne, It also appeared that ionic strength (estimated by conductivity) c
ould influence the hydrophobic properties of oocysts, Cryptosporidium
oocysts showed a pH-dependent surface charge, with zeta potentials bec
oming less negative as pH was reduced, starting at -35 mV for alkaline
pH and reaching 0 at isoelectric points for pH 2.5, On the other hand
, variation of surface charge with respect to conductivity of the susp
ension tested in this work was quite small, The knowledge of hydrophob
ic properties and surface charge of the parasite provides information
useful in, for example, the choice of various flocculation treatments,
membrane filters, and cleaning agents in connection with oocyst recov
ery.