New and Uncommon Fatty Acids in Lipids of Deep-Sea Foraminifera.

Fatty acids (FA) of agglutinating foraminifera of two genera, Bathysiphon and Rhabdammina, collected from a depth of 3307-3377 m in the Kuril Basin, Sea of Okhotsk, and adjacent deep-sea waters of the Pacific Ocean, were analyzed. In lipids of two Bathysiphon species, in addition to common FA typical for marine organisms, the uncommon ∆4 and ∆7 monoenoic acids and ∆4,7-dienoic acid were found in noticeable amounts. FA of two Rhabdammina species included also such uncommon acids as ∆5,8,11,14-21:4, ∆5,8,11,14-22:4, and ∆5,8,11,14-23:4, which are homologues to arachidonic acid. High levels of cis-vaccenic and arachidonic acids were typical for lipids of all the studied species. At the same time, we observed a substantial difference in FA composition between members of these two genera. Using GC and GC-MS of FAME, pyrrolidide and DMOX derivatives, the structures of 10 new FA were confirmed: ∆4-i-16:1 (1.1-0.6%), ∆7-i-21:1 (0.4%), ∆7-ai-21:1 (0.3-0.8%), ∆4,11-18:2 (0.3-0.9%), ∆4,7-20:2 (8.8%), ∆7,12-20:2 (0.4-0.6%), ∆4,7-21:2 (0.6%), ∆7,12-22:2 (6.4-2.1%); ∆5,8,11,14-22:4 (1.2-2.0%), and ∆5,8,11,14-23:4 (1.7-2.3%). The origin of the new FA and the role of foraminifera FA in deep-sea communities are discussed.