The Polyunsaturated Fatty Acids of Marine and Freshwater Cryptomonads1

SYNOPSIS Fatty acids were examined of photosynthetic and non‐photosynthetic marine and freshwater cryptomonads cultured as photoauxotrophs, photoheterotrophs and heterotrophs at various incubation temperatures and constant light intensity. Photo‐synthetic marine and freshwater forms contained octadecatrienoic, octadecatetraenoic, eicosapentaenoic and docosahexaenoic (all‐cis, ω3 acids) as the major polyunsaturates, and a freshwater heterotroph contained mostly the octadecatrienoic acid. The polar lipids of a marine, photosynthetic form, Cryptomonas sp., included the usual thylakoid membrane lipids of the chloroplasts of eukaryotic, photosynthetic cells: galactosyl diglycerides, phosphatidyl glycerol and a sulfolipid. Also present were 2 choline‐containing phospholipids: phosphatidyl choline and an unknown. Ninhydrin‐positive and inositol‐containing lipids were not detected. Octadecatetraenoic acid comprised 75% of the total fatty acids of the monogalactosyl diglyceride fraction. The phosphatidyl glycerol was acylated mostly by ω13 trans‐hexadecaenoic acid and the eicosapentaenoic acid. Evolutionary relationships of cryptomonads as mirrored in lipid composition are discussed.