Chemotaxonomic survey of sterols and fatty acids in six marine raphidophyte algae

Fatty acid and sterol profiles allowed for clear discrimination between the raphidophyte genera Chattonella, Heterosigma, Fibrocapsa and Olisthodiscus, but exhibited little differentiation for individual Chattonella species(C. marina, C. antiqua and C. subsalsa). Sterol and fatty acid profiles do not support the separation of Chattonella antiqua and C. marina as distinct species. Ecophenotypic variations in lipid profiles were also observed between Chattonella strains from different geographic locations. Sterol signatures which may be useful as chemotaxonomic markers were: the absence of C-27 sterols (cholesterol and 24-dihydrozymosterol) in Heterosigma akashiwo; the presence of isofucosterol in Chattonella; and the occurrence of brassicasterol, poriferasterol and fucosterol in Olisthodiscus luteus. High levels of eicosapentaenoic acid (EPA; 17-27% of fatty acids) were present in all raphidophyte species. Lipid composition correlated more closely to recent molecular classification of raphidophytes than carotenoid pigments.