The effects of some factors on the growth and morphology of Naegleria sp. and three strains of the genus Acanthamoeba.

The effects of various biophysical and chemical factors on the cytology of vegetative stages of Naegleria sp., Vitek strain, Acanthamoeba culbertsoni, Acanthamoeba castellanii, Neff strain and Acanthamoeba polyphaga, No. 1289, were studied. The amoebae were cultured in a liquid medium under axenic conditions. The optimum temperature was 37 degrees C for pathogenic strains of Naegleria sp. and Acanthamoeba culbertsoni and 20 degrees C for A. castellanii. No changes were observed in the growth of A. polyphaga at the temperatures 20 degrees and 37 degrees C. The strains investigated grew at pH values of 5.6 to 7.7 using Soerensen's buffer. At the limit values the growth was inhibited and the morphology of cells was markedly changed. All of the four strains grew still at pH 8.4 kept by NaHCO3. A. polyphaga grew at partial anaerobiosis. The three tested strains of the genus Acanthamoeba grew in liquid axenic medium with 0.89% NaCl. The growth of Naegleria sp., Vitek was inhibited already at 0.2% concentration of this salt. The addition of 3 X 10(-2) m KCl to the culture medium had a harmful effect on the growth and morphology of three tested strains, except A. polyphaga. In the culture medium containing 2 X 10(-3) m CaCl2 the encystment of both pathogenic strains was stimulated. The cytological changes under experimental conditions were manifested by atypical movement of trophozoits and their intracellular structure.