LONG-TERM PRESERVATION OF TETRASELMIS-SUECICA - INFLUENCE OF STORAGE ON VIABILITY AND FATTY-ACID PROFILE

Aquaculture production could be improved by using preserved microalgal biomass as feedstuff for marine animal larvae and juveniles. The pres ent paper reports the effects of preserving Tetraselmis suecica by fre ezing with and without cryoprotectant, freezing in liquid nitrogen and maintenance of concentrated cultures at 4 degrees C on viability and fatty acid profile. For long-term preservation (as long as 21 months), freezing can keep the fatty acid profile unaltered although leading to complete loss of cell viability. On the other hand, concentrated cult ures kept in darkness at +4 degrees C show a strong capacity for survi val closely correlated with cell concentration. At 4 g . 1(-1), residu al photosynthetic activity (ca. 6% of the initial) was still present a fter 150 days of storage. Furthermore, oxygen availability affected ce ll survival. Cultures stored in hermetically sealed vials lost their v iability much more rapidly than those kept in cotton-plugged vials. Dr y weight percentages of all fatty acids slightly increased in stored b iomass in comparison with fresh biomass, because of reserve material c onsumption. Nonetheless, the fatty acid profile on a total fatty acid basis remained unchanged over storage time regardless of viability. Th is is an important fact to bear in mind as fatty acids play an importa nt role in the quality of the cell as food in aquaculture.