A method for cryopreservation of the Tetraselmis tetrathele (Prasinophyceae, chlorophyta)
1997
Terauchi, E. (Tokai Univ., Tokyo (Japan)) | Kuwano, K. | Okauchi, M. | Saga, N.
Cryopreservation of the marine microalga Tetraselmis tetrathele (NRIA) strain, which is widely used in the aquaculture industry as a food organism, by the two-step freezing method was attempted. A solution composed of 10 to 15% dimethyl sulfoxide (DMSO) and 0.5M sorbitol in 50% seawater had the favorable cryoprotective effect on cells of the strain. The cells from an exponential phase of growth were found to be sensitive to stresses of freezing and thawing. In contrast, cells from a stationary phase of growth were resistant to these stresses. The most appropriate cryopreservation procedure was as follows: DMSO was added gradually over a period of 15 min followed by an equilibration period of 45 min. The cells were then prefrozen to -40 degrees C at 0.1-1.0 degrees C/min prior to immersion in LN2 (Liquid Nitrogen). After storage in LN2, the cell suspension was thawed quickly by agitation of the vial in a water bath at 40 degrees C, and the cryoprotectants were washed off by gradual dilution with seawater. The survival rate determined by vital staining with erythrosin was about 90%. The cell was independent of the period of storage at least 210 days
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