EFFECT OF LIGHT CYCLE ON DIATOM FATTY ACID COMPOSITION AND QUANTITATIVE MORPHOLOGY¹

Abstract

Quantitative cytological and fatty acid composition was determined for the diatom Cyclotella meneghiniana Kütz, Data from four separate experiments were examined to elucidate changes that may occur with respect to daily photoperiod. Overall, fatty acid composition is similar to that reported for other diatoms with the exception that the C16 fatty acids constitute approximately 70% of all fatty acids. The major fatty acids are C14:0, 16:1, 16:0, 18:0, and 20:5. Fatty acids that are present in minor amounts are iso‐14:0, iso‐15:0, 15:0, 17:0, 18:4, 18:2, 18:1, 19:0, 20:0, 22:0, and 23:0. Cytological composition is similar to that previously reported with the chloroplast and vacuole being the largest compartments within the cell. Changes in both cytological and fatty acid composition were studied with respect to the light / dark cycle. Chloroplast and lipid relative volume are greatest during the early part of the dark period. Nuclear relative volume is lowest in the dark and increases throughout the light period. Total unsaturated fatty acids, including the C20:5 fatty acid, are lowest in the early part of the light period and highest in the dark. The sum of the C16 fatty acids remains constant at 70% of total fatty acids in the cells throughout the light/dark cycle, although percent composition of these two fatty acids shifts. The data suggest that cyclical changes occur in both quantitative morphology and fatty acids composition with respect to daily photoperiod. The cells, although not rigidly synchronized, most likely divide in the latter part of the dark period or in the first hours of the light period. Lipids increase dramatically in the dark. The ecological implications of lipid storage are discussed in relation to lipophilic toxicants.

Effect of light intensity on the fatty acid composition of dinoflagellates symbiotic with hermatypic corals

“…Similar results were reported for the total lipids of some species of diatoms (Sicko-Goad et al 1988, Thompson et al 1990) and the eustigmatophyte Nanochloropsis sp. The fatty acid 16:1(n-7) showed a positive correlation in its percentage abundance in TAG with PAR.…”

Chromatographic characterization of triacylglycerides and fatty acid methyl esters in microalgae oils for biodiesel production

“…contains more palmitoleic acid (41.0%), oleic acid (11.6%), and DHA (6.2%) than other microalgae of the same class. A similar pattern was found in other microalgae of the same genus, Cyclotella meneghiniana 25 and Cyclotella cryptic. 26 Cyclotella species can accumulate a lipid content of about 42% in their dry biomass.…”

Does a large-scale continuous algal production system provide a stable supply of fatty acids to bivalve hatcheries?

“…Brown et al 1989Brown et al , 1997. The biochemical composition of microalgae is affected by the growth environment which can be manipulated by changing the culture medium (Wikfors et al 1984;Ben-Amotz et al 1985), temperature (Redalje and Laws 1983;James et al 1989), stage of harvest (Chu et al 1982;Whyte 1987) and light conditions (Caron et al 1988;Sicko-Goad et al 1988;Cohen et al 1988; Thompson et al 1990). …”