Acanthamoeba strains lose their abilities to encyst synchronously upon prolonged axenic culture.

To evaluate the influence of prolonged axenic culture on the encystment capacity of Acanthamoeba spp., the encystment potential of four closely related Acanthamoeba strains, subcultured axenically for different periods of time, was evaluated comparing five encystment media. Media with more alkaline pH values were slightly more effective; however, the composition of the respective encystment medium had only limited influence on the encystment potential, while a strong correlation of losses in encystment potential and times strains had been cultured axenically was demonstrated. Furthermore, our results indicate that losses in encystment potential occur shortly after transfer into axenic culture to remain constant over many years.