Received 18 April 1989. Accepted 28 June 1989.
REGULATION OF FATTY ACID COMPOSITION BY IRRADIANCE LEVEL IN THE EUSTIGMATOPHYTE NANNOCHLOROPSIS SP.1
Article first published online: 29 OCT 2004
Journal of Phycology
Volume 25, Issue 4, pages 686–692, December 1989
How to Cite
Sukenik, A., Carmeli, Y. and Berner, T. (1989), REGULATION OF FATTY ACID COMPOSITION BY IRRADIANCE LEVEL IN THE EUSTIGMATOPHYTE NANNOCHLOROPSIS SP.. Journal of Phycology, 25: 686–692. doi: 10.1111/j.0022-3646.1989.00686.x
This research was supported by the Arava R&D Authority and by the Strauss/Hanauer Memorial Fund, Inc. Additional support was provided by the U.S.-Israel Binational Science Foundation under grant 86-00376. The technical help of Ms. Y. Chanania and the personnel of the Electron Microscopy Unit, Bar Ilan University, is gratefully acknowledged.
- Issue published online: 29 OCT 2004
- Article first published online: 29 OCT 2004
- cell morphometry;
- chemical composition;
- eicosapentaenoic acid;
- fatty acids;
- light intensity;
- light-shade adaptation;
Chemical composition and quantitative cytological measurements were determined for the eustigmatophyte Nannochloropsis sp. Cultures were grown in turbidostats at three irradiance levels: growth-limiting light, growth-saturating light and photoinhibiting light. Cellular chlorophyll a content decreased as irradiance level increased, concomitant with a disproportionate reduction in carotenoid content. Nannochloropsis sp. grown in saturating light was characterized by a high content of lipid, fatty acids and carbohydrate compared with cells grown in light-limiting conditions. The increase in cellular lipid content coincided with a reduction in the percentage of eicosapentaenoic acid (C20:5) and arachidonic acid (C20:4), fatty acids that are mainly associated with galactolipids, and with an increase in the relative abundance of palmitic acid (C16:0) and palmitoleic acid (C16:1). At growth limiting light conditions, Nannochloropsis sp. preferentially synthesized galactolipids; however, as growth became light saturated, relatively more neutral lipids, mainly triacylglycerols, were synthesized. Changes in lipid content and composition were qualitatively related to changes in cell morphology. Cells grown under low light conditions were characterized by a large relative volume of chloroplast, high surface density of thylakoid membranes and low relative volume of lipid storage bodies. The physiological implications of the changes in cellular lipid composition and ultrastructure are discussed in relation to light/shade adaptation.