T. V. Bosh, P. Q. Long - Comparison of the composition of wax ester molecular species of different coral groups (subclasses Hexacorallia and Octocorallia)

BIOLOGIYA MORYA, 2017, Vol. 43, No. 6, pp. 436-443

Comparison of the composition of wax ester molecular species of different coral groups (subclasses Hexacorallia and Octocorallia)

¹National Scientific Center of Marine Biology FEB RAS, Vladivostok 690041;
²Institute of Natural Product Chemistry VANT, Hanoi, Vietnam

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The chemical structures and the content of wax ester molecular species were determined for the first time in nine coral species from three taxonomic groups - symbiotic reef-building corals, (subclasses Hexacorallia), symbiotic soft corals alcyonarians, and asymbiotic soft corals gorgonians (subclasses Octocorallia) collected in the South China Sea (Vietnam). Our comparison of these groups showed that the absence of symbiotic microalgae (zooxanthellae) and the exoskeleton affects considerably the profile of molecular species of wax esters. The main components of wax esters of all corals were cetyl palmitate (16:0-16:0) and other saturated wax esters containing 30, 34, and 36 carbon atoms. The content of unsaturated molecular species 6:0-16:1, 16:0-18:1, and 16:0-20:1 in wax esters of symbiotic soft corals (alcyonarians) was greater than that in wax esters of reef-building corals. In contrast to symbiotic coral species, wax esters of asymbiotic soft corals, namely azooxanthellate gorgonians, contained a considerable amount of long-chain molecular species (C₃₇-C₄₁) with an odd number of carbon atoms. The presence of such molecular species indicates that asymbiotic gorgonians may use bacterial FAs in biosynthesis of their own wax esters. This observation confirms our hypothesis that bacterial community is important for maintaining the energy balance of azooxanthellate corals.

Key words: wax esters, lipid molecular species, corals, associated microorganisms, lipidomics.