7. Preservation of Protozoan Cultures(Microorganism,Lectures presented at the Seminar of Japanese Society for Research of Freezing and Drying : "Maintenance of Biological Genetic Resources")

Abstract

Protozoa constitute a huge group of eukaryotic microorganisms which include free-living and parasitic species. In this article, methods of preservation of a few species of ciliated protozoa which are often used for genetical researches are reviewed. The nasty problem in the preservation of genetic stocks of ciliated protozoa is aging and limited life span. To prevent aging, maintenance of cultures in low temperature and in a medium containing solid or particular nutrients are often used. Preservation in frozen conditions is only successful for Tetrahymena. Limited success was reported in Paramecium but recovery ratio is very low. Much study is needed for improving the preservation of ciliates in frozen state.