REGULATION OF FATTY ACID COMPOSITION BY IRRADIANCE LEVEL IN THE EUSTIGMATOPHYTENANNOCHLOROPSISSP.¹

Abstract

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.

Effect of light and feeding on the fatty acid and sterol composition of zooxanthellae and host tissue isolated from the scleractinian coral Turbinaria reniformis

“…1a,b), because photosynthetically fixed C might not meet the needs for both the coral metabolism and lipid accumulation in the tissue (Anthony et al 2002). This reduced energy investment was also shown in the corals Goniastrea retiformis and Porites cylindrica (Anthony and Fabricius 2000) and in the Nannochloropsis algae (Sukenik et al 1989). At low light, however, feeding increased lipid concentrations and rates of calcification, suggesting that the energy gained by feeding goes into these two processes.…”

Influence de la température, de l'intensité lumineuse et du stade de croissance sur la composition biochimique deChlorella sorokinianaShihira & Krauss

“…Parmi les facteurs affectant les proportions en lipides chez les microalgues, on peut citer : -la température (Aaronson 1973, Tedesco & Duerr 1989, Tan & Johns 1991, -l'intensité lumineuse (Sukenik et al 1989, Tedesco & Duerr 1989, Harrison et al 1990, Renaud et al 1991, -la photopériode (Shifrin & Chisholm 1981), -la concentration en C0 2 du milieu de culture (Becker & Venkatamaran 1980), -la concentration et la nature de la source azotée (Shifrin & Chisholm 1980, Kost et al 1984, Thomas et al 1984a,b, Ben-Amotz et al 1985, Harrison et al 1990, Chen & Johns 1991, -la concentration en silice, dans le cas des Diatomées (Shifrin & Chisholm 1981), -la pression osmotique du milieu (Ben-Amotz et al 1985, Al Hassan et al 1990 -le stade de croissance (Dubinsky et al 1978, Piorreck et al 1984, Barclay et al 1985.…”

Microalgal triacylglycerols as feedstocks for biofuel production: perspectives and advances

“…Typically, low light intensity induces the formation of polar lipids, particularly the membrane polar lipids associated with the chloroplast, whereas high light intensity decreases total polar lipid content with a concomitant increase in the amount of neutral storage lipids, mainly TAGs (Brown et al, 1996;Khotimchenko and Yakovleva, 2005;Napolitano, 1994;Orcutt and Patterson, 1974;Spoehr and Milner, 1949;Sukenik et al, 1989).…”