Isolation, fatty acid profiles and cryopreservation of marine thraustochytrids from mangrove habitats in Thailand

Thraustochytrids, marine protists, have attracted attention as a proven alternative source of polyunsaturated fatty acids (PUFAs). We isolated a high diversity of thraustochytrids from Thailand and tested their potential use in the production of high-value fatty acids. The isolated thraustochytrids can be categorized into seven major groups based on unique morphological features, molecular phylogeny and fatty acid profiles. Two of the seven isolated thraustochytrid groups could potentially be new lineages in the Labyrinthulomycetes. The production of total fatty acid (TFA) from these thraustochytrids ranged from 2.4 to 35.6% (w/w), with biomass varying from 0.3 to 8.9 g l(-1). The production of arachidonic acid (C20:4) ranged from 0.3 to 8.2% of TFA, eicosapentaenoic acid (C20: 5) from 1.5 to 12.4%, docosapentaenoic acid (C22:5) from 9.7 to 27.3%, and docosahexaenoic acid (C22:6) from 14.4 to 51.7%. In addition, the cryopreservation of selected thraustochytrids at -80 degrees C with 10% glycerol, the combination of 5% trehalose and 10% glycerol, and freezing in vapor-phase liquid nitrogen were found to maintain significant cell viability. The information provided in this study could be applied to cryopreservation and biotechnological applications of the economically valuable marine Labyrinthulomycetes from Thailand.