Cryopreservation of Algae

Only microalgae (algae with cell/filament/thallus size <2 mm) are considered in this chapter. However, the methods described are applicable to a wide variety of prokaryotic cyanobacteria and eukaryotic microalgae. Most culturable cyanobacteria and soil microalgae that have been examined can be cryopreserved with relatively high viability. Furthermore, many freshwater and marine eukaryotic algae can also be cryopreserved, but usually with lower viability. Marine diatoms can be cryopreserved, and often have high viability (Day and Brand 2005), although there has been limited success preserving freshwater diatoms (McLellan 1989).

It has been observed that chlorarachniophytes, eustigmatophytes, pelagophytes, phaeothamniophytes and ulvophytes often have very high success rates, comparable to the other green algae and cyanobacteria (Day and Brand 2005). However, to date, most morphologically complex taxa including members of the dinoflagellates, cryptophytes, synurophytes and raphidophytes cannot be successfully cryopreserved. It is anticipated that further research on the basic mechanisms of freezing damage and the empirical development of improved protocols will continue to expand the number and diversity of algal taxa responsive to cryopreservation techniques.