STEROLS AND ALKENONES OF ISOCHRYSIS

Sterols were identified and quantified in six marine microalgal strain s identified as belonging to the prymnesiophyte genus Isochrysis; seve ral of these strains are in wide use in the commerical mariculture ind ustry. One strain contained only cholesterol, and another contained a complex mixture of Delta(5)-sterols and dihydroxysterols. Two strains contained brassicasterol and two others contained epibrassicasterol as the principal sterol. The strains containing brassicasterol or epibra ssicasterol also contained long chain alkenones characteristic of some members of the Prymnesiophyceae; whereas, those without brassicastero l or epibrassicasterol contained no long chain alkenones. These qualit ative biochemical differences appear to have taxonomic significance an d may be important in the value of these algae as live feeds for reari ng marine invertebrates.