Cryopreservation of the edible alkalophilic cyanobacterium Arthrospira platensis
Efficient cryopreservation conditions for the edible alkalophilic cyanobacterium Arthrospira (Spirulina) platensis were investigated using a model strain A. platensis NIES-39. As a result, it was found that more than 60% of cells were viable upon thawing, when they had been frozen at a cooling rate of approximately −1 °C min−1 in the presence of 10% (v/v) dimethyl sulfoxide. Further examination with other Arthrospira strains showed that many of them had strain-dependent optimal conditions for cryopreservation. For example, the best freezing conditions for A. platensis SAG 21.99 were snap-freezing in liquid nitrogen in the presence of 5% (v/v) dimethyl sulfoxide, while they were slow cooling at approximately −1 °C min−1 in the presence of 10% (v/v) methanol for A. platensis NIES-46, NIES-2308 and UTEX 1926. The variety of successful cryopreservation conditions presented in this study is useful when attempting to cryopreserve various Arthrospira strains.
The conditions for efficient cryopreservation of Arthrospira platensis were determined. They enable genetically stable preservation of many A. platensis strains.