Maintenance of Acanthamoeba culbertsoni by cryopreservation.

In order to determine the viability of trophozoites of Acanthamoeba culbertsoni under cryopreservation conditions, cultures in serum-casein-glucose-yeast extract medium were subject to 5%, 7.5%, and 10% concentrations of dimethylsulfoxide (DMSO). With the methodology followed, the percentages of recovery varied between 75.6% and 86.6% with DMSO at 10%, between 54.5% and 73.5% with DMSO at 7.5%, and between 43.6% and 68.5% with DMSO at 5%. The amebae were kept in liquid nitrogen for 30-210 days. The highest viability of trophozoites was founded when DMSO was used at a final concentration of 10% and an equilibrium temperature of 4 C. Gross cultural or morphological changes were not noted in trophozoites thawed from frozen suspensions.