Palusinska-Szysz, M; Turska-Szewczuk, A; Karas, M; Russa, R; Drozanski, WJ
The cellular fatty acid composition of Acanthamoeba castellanii, a unicellular bacteriovorous organism, was reinvestigated. Lipids froth amoebae grown axenically in proteose peptone-yeast extract-glucose medium were extracted with chloroform-methanol and separated by silicic acid column chromatography into non-polar and polar fractions. The fatty acid composition of the lipids and the double-bond position of the unsaturated acids have been determined by capillary gas chromatography-mass spectrometry (GC-MS) of their corresponding methyl esters, 2-alkenyl-4,4-dimetlryloxazoline (DMOX) derivatives and dimethyldisulfide (DMDS) adducts. Evidence is given that lipids from A. castellanii in addition to the three already identified saturated straight chain fatty acids: tetradecanoic (C14:0), hexadecanoic (C16:0), octadecanoic (C18:0), and six preponderant unsaturated fatty acids: hexadecenoic (C16:1 Delta(7)), octadecenoic (C18:1 Delta(9)), octadecadienoic (C18:2 Delta(9,12)), eicosadienoic (C20:2 Delta(11,14)),eicosatrienoic (C20:3 Delta(8,11,14)), and eicosatetraenoic (C20:4 Delta(5,8,11,14)), contain additionally four very long chain unsaturated fatty acids: octacosenoic (C28:1 Delta(21)),octacosadienoic (C28:2 Delta(5,21)), triacontadienoic (30:2 Delta(21,24)), and triacontatrienoic (C30:3 Delta(5,21,24)) previously unreported in lipids of A. castellanii. These new long chain fatty acids account for approximately 25% of total fatty acids. To our knowledge, this is the first report of very long chain polyenoic fatty acids present in lipids extracted from A. castellanii cells.