FATTY-ACID COMPOSITION OF BACTERIA ASSOCIATED WITH THE TOXIC DINOFLAGELLATE OSTREOPSIS-LENTICULARIS AND WITH CARIBBEAN PALYTHOA SPECIES

The fatty acid composition of a Pseudomonas sp. (Alteromonas) and its host, the dinoflagellate Ostreopsis lenticularis, vectors in ciguatera fish poisoning, has been studied. The major fatty acids in O. lenticu laris were 16:0, 20:5n-3, and 22:6n-3, but 18:2n-6, 18:3n-3, and 18:n- 3 were also identified. In contrast to other dinoflagellates, 18:5n-3 was not detected in O. lenticularis. Even-chain fatty acids such as 9- 16:1, 11-18:1, and 13-20:1 predominated in the Pseudomonas sp. from O. lenticularis, but 16-20% of (E)-11-methyl-12-octadecenoic acid was al so identified. The chirality of the latter was confirmed by total synt hesis (28% overall yield) starting from oxacyclotridecan-2-one. The fa tty acid compositions of two other Pseudomonas species, from the palyt oxin-producing zoanthids Palythoa mamillosa and P, caribdea, were also studied and were similar to that of the Pseudomonas sp. from O. lenti cularis. The possibility of using some of these fatty acids as chemota xonomic lipids in identifying marine animals that consume toxic dinofl agellates or zoanthids is discussed.