Cryopreservation of a water‐bloom forming cyanobacterium, Microcystis aeruginosa f. aeruginosa

Abstract

SUMMARYA method for the Cryopreservation of Microcystis aeruginosa f. aeruginosa is described. For the five strains tested, dimethyl sulfoxide (DMSO) (3% v/v) was the only effective cryoprotectant for freezing to, and thawing from ‐196°C and allowed the successful recovery (>50%) of all the strains. The viability of frozen material was independent of the period of storage in liquid nitrogen. The strain NIES‐44 (National Institute for Environmental Studies) had a recovery level of greater than 90% at 3–10% (v/v) DMSO in both two step and rapid cooling methods. The other three strains, NIES‐87, 88 and 89 had greater than 60% of viability after freeze/thawing in presence of both 3% and 5% DMSO concentrations. On the other hand, the strain NIES‐90 showed approximately 50% of viability in only 3% DMSO solution after two step cooling to and thawing from ‐196°C. This strain was damaged by greater than 4% DMSO and by rapid cooling to ‐196°C. It was found that cold shock injury and the cytotoxicity of DMSO were different at a strain level.