Effect of growth temperature on the cryopreservation of prototheca.

The temperature at which Prototheca spp. were grown determined their response to freezing to -196 degrees C and subsequent thawing. Cells cultured at 35 degrees C were the most sensitive to freezing injury; at lower growth temperatures, resistance to freezing damage was seen. At all culture temperatures examined, the freezing tolerance varied with the age of the culture.