STEROL, FATTY-ACID, AND PIGMENT CHARACTERISTICS OF UTEX-2341, A MARINE EUSTIGMATOPHYTE IDENTIFIED PREVIOUSLY AS CHLORELLA-MINUTISSIMA (CHLOROPHYCEAE)

An examination of the sterols of UTEX 2341, a small (ca. 2 mu m), nonm otile unicellular marine alga identified as Chlorella minutissima Fott et Novakova, yielded results inconsistent with any of 35 Chlorella st rains analyzed previously. UTEX 2341 contained cholesterol as the prin cipal sterol, with 24-methylenecholesterol, fucosterol, and isofucoste rol also present; these are not dominant sterols in any other Chlorell a species. Presence of eicosapentaenoic acid in UTEX 2341 also contras ted with fatty acids of Chlorella strains analyzed previously. Pigment analysis of UTEX 2341 revealed that it contained chlorophyll a, but n ot chlorophylls b or c; violaxanthin was the only major xanthophyll pi gment. Both lipid and pigment compositions suggest that UTEX 2341 is n ot a member of the genus Chlorella but, rather, belongs in the Eustigm atophyceae it may be Nannochloropsis sp. Cells with possible extracell ular structures were present at an appreciable percentage of the stati onary-phase population studied; centrifuging removed or collapsed thes e structures. The high cholesterol and polyunsaturated fatty acid cont ents of UTEX 2341 make it attractive as a potential aquaculture feed, provided it is, or can be made, digestible.