| pubmed-article:20309503 | pubmed:abstractText | Cultures of the recalcitrant microalga Porphyridium aerugineum were cryopreserved. A two-step, uncontrolled rapid freezing protocol, using methanol as cryoprotectant resulted in 23.8 percent viable cells. Cultures in the exponential growth phase, grown under low light intensity to prevent vacuole formation in cells, cryopreserved using a passive freezer, showed 22.4 percent viability. This value was enhanced to 31.5 percent when a controlled-rate freezer was employed. Optimized cultures in the exponential growth phase, cultivated in medium supplemented or not with vitamin B12, were then tested for freezing using the encapsulation-dehydration protocol. High cell loss was observed early during the sorbitol dehydration steps, but 63.6 percent of the remaining encapsulated cells were viable after thawing. This study confirmed the potential of encapsulation-dehydration as a method allowing to improve the low viability obtained with two-step freezing protocols. It also showed the importance of monitoring the response of algal cells to bead osmotic and evaporative dehydration pretreatments before freezing. | lld:pubmed |
