Microalgal cryo-preservation using dimethyl sulfoxide (Me sub(2)SO) coupled with two freezing protocols: Influence on the fatty acid profile

Procedures 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 slo...

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Bibliographic Details
Published in:Journal of thermal biology 2010-05, Vol.35 (4), p.175-181
Main Authors: Guermazi, Wassim, Sellami-Kammoun, Alya, Elloumi, Jannet, Drira, Zaher, Aleya, Lotfi, Marangoni, Roberto, Ayadi, Habib, Maalej, Sami
Format: Article
Language:English
Subjects:
Algae
C (programming language)
Cooling
Dimethyl sulfoxide
Fatty acids
Freezing
Liquid nitrogen
Viability
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Summary:Procedures 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: Me sub(2)SO 5% v/v). After 20 min at 4 C, the midi-straws were filled and cooled slowly (1.5 C min super(-1)) to -140 C, by a programmable freezer (Digitcool - IMV), before putting them directly into liquid nitrogen. Fast freezing was performed with 10% or 15% Me sub(2)SO 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 Me sub(2)SO was good for all the selected algae (C. vulgaris >95%, I. galbana and D. salina >70% of the control), applying the slow cooling. The post-thawed viability without Me sub(2)SO 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.
ISSN:0306-4565
DOI:10.1016/j.jtherbio.2010.03.001