MODIFICATION OF FATTY-ACID COMPOSITION IN HALOPHILIC ANTARCTIC MICROALGAE

The major fatty acids in two Dunaliella isolates originating from Anta rctic hypersaline lakes were 18:3 omega 3, 16:0, 16:4 omega 3. 18:1 om ega 9, 18:2 omega 6, and 16:1 omega 7. The relative amount of individu al fatty acids was modified by partially,or fully replacing ionic osmo tic pressure (Na+, K+ and Cl-) with molecular osmotic pressure (sorbit ol) in the growth medium. The effects of sorbitol on the extent of cel lular fatty acid unsaturation differed in the two isolates. The result s suggest that the appropriate environment necessary for the growth of these ''halophilic'' species is a certain level of osmotic pressure i n the medium, but that this can be provided by either ionic or molecul ar osmotic pressure, or a mixture of both. (C) 1998 Elsevier Science L td. All rights reserved.