Anno2010
AutoriGuermazi W, Sellami-kammoun A, Elloumi J, Drira Z, Aleya L, Marangoni R, Ayadi H, Maalej S
AbstractProcedures for determining the optimal pre-freezing protocol for cryo-preservation of microalgae are discussed. Three algal species were used (Chlorella vulgaris, Isochrysis galbana and Dunaliella salina) and cryo-stored using two different methods: the slow cooling and the fast freezing. In the slow cooling, each algae batch was treated with or without cryo-protectant (dimethyl sulfoxide: Me2SO 5% v/v). After 20 min at 4 degrees C, the midi-straws were filled and cooled slowly (1.5 degrees C min(-1)) to -140 degrees C, by a programmable freezer (Digitcool-IMV), before putting them directly into liquid nitrogen. Fast freezing was performed with 10% or 15% Me2SO prior to plunging into liquid nitrogen. The three algal species followed the same re-growth pattern as that of the controls. The post-thawed viability with Me2SO was good for all the selected algae (C. vulgaris > 95%, I. galbana and D. sauna > 70% of the control), applying the slow cooling. The post-thawed viability without Me2SO was 60% for I. galbana, 52% for D. salina and 33% for C. vulgaris. Fast freezing was not suitable for cryo-storage of I. galbana but gave good post-thawing viability for D. salina (70%). The decrease in fatty acid content of the cryo-stored algae was influenced by the temperature. The rapid decrease in temperature induced by fast freezing can explain the low level of fatty acid content of the three cryo-stored algae. Fatty acid profiles show that the nutritional values of the three cryo-stored micro-algae were not significantly affected especially when treated with slow cooling protocols.
RivistaJournal Of Thermal Biology
ISSN
Impact factor
Volume35
Pagina inizio175
Pagina fine181
Autori IBFRoberto MARANGONI
Linee di Ricerca IBFMD.P01.003.001
Sedi IBFIBF.PI