Lipid class and fatty acid composition of the protozoan parasite of oysters, Perkinsus marinus cultivated in two different media

The meront stage of the oyster protozoan parasite. Perkinsus marinus, culti vated in two media with different fatty acid profiles was analyzed for its fatty acid and lipid class composition. The composition of fatty acids in t he prezoosporangium stage of the parasite as well as that of the host oyste r were investigated. Although the lipid class composition of meronts was do minated by phospholipids and triacylglycerol, there was no triaclgycerol de tected in either culture medium. Despite the difference in fatty acid compo sition of the two media, the fatty acid composition of meronts in each medi um was dominated by 14:0, 16:0, 18:0, 18:1(n-9), 20:1(n-9), 18:2(n-6) and 2 0:4(n-6), a profile that differed from its host. The quantities of total li pids and fatty acids in meronts increased as the number of meronts increase d and far exceeded the initial amounts in the media and in the initial cell inoculum. The meronts harvested 25 d post-inoculation. had about 3 to 6 ti mes higher total lipids and 4 to 13 times higher fatty acids than the amoun ts contained in the media. The fatty acid profiles of both prezoosporangia and oysters resembled each other and consisted primarily of 16:0, 20:4(n-6. 20:5(n-3), 22:2 Delta7,15, and 22:6(n-3). These results indicate that duri ng meront proliferation, the parasite synthesizes certain fatty acids and l ipid classes. For development from meront to prezoosporangium, the parasite may rely on its host for lipid resources.