Patterns of variation in the lipid class and fatty acid composition of Nannochloropsis oculata (Eustigmatophyceae) during batch culture

Abstract

Changes in the lipid and fatty acyl compositions of the marine microalga Nannochloropsis oculata Droop were examined during a batch culture growth cycle. During the early phase of batch culture the cellular proportion of triacylglycerols (TAG) increased. This was in addition to the increases in TAG observed in many microalgal species in the stationary-phase. Concomitant increases in the relative proportions of both saturated and monounsaturated fatty acids and decreases in the proportion of polyunsaturated fatty acids in total lipid were also associated with this phase. The separated individual lipid classes were found to have characteristic fatty acyl compositions. The relative proportion of lipid per cell, the relative proportions of the individual lipid classes and the fatty acyl compositions of the individual classes were all subject to variability during the growth cycle. The changing total lipid fatty acyl composition of N. oculata was found to be determined by the proportion of the total lipid present as TAG. The data suggest that the changes observed in the fatty acyl composition of N. oculata are a result of the partitioning of photosynthetically fixed carbon between polar and neutral lipid class biosynthesis and fatty acyl desaturation and elongation pathways. The effect of such a partitioning of carbon is discussed in relation to the effects of environmental variables and growth phase upon the balance of lipid class and polyunsaturated fatty acids (PUFA) synthesis in marine microalgae.

Effects of Light and Temperature on Fatty Acid Production in Nannochloropsis Salina

“…The latter is a precursor for the former [14] indicating potential down-regulation of the fatty acid saturation and elongation pathway as a response to energy limitation. An increase in oleic acid is indicative of an increasing proportion of phospholipids (e.g., phosatidylcholine) at the expense of galactolipids (e.g., monogalactosyldiacylglycerol) according to previous reports of fatty acid distribution in lipid classes [15][16][17]. The proportion of oleic acid detected here (~20%) exceeds all previously reported values (Khozin-Goldberg [18] found 13% in some cases).…”

Acyl lipid composition variation related to culture age and nitrogen concentration in continuous culture of the microalga Phaeodactylum tricornutum

“…Probably, this state represents an`optimum' for P. tricornutum cells as suggested by the fact that biomass productivity reached a maximum at this dilution rate; the biomass productivity decreased when culture was moved in either direction from this optimum point (data not shown). A reduction in polar lipids and an increase in TAG are usually associated with culture ageing (A Â lvarez Cobelas, 1989;Hodgson et al, 1991;Dunstan et al, 1993;Lombardi and Wangersky, 1995;Brown et al, 1996), however, the speci®c response may be dierent in dierent microalgae (Lombardi and Wangersky, 1995), or the response may depend on the steady state reached as shown in this work. When dilution rate increases (i.e.…”

“…Increase in lipid content is usually associated with culture ageing (i.e., stationary phase) Siron et al, 1989;Hodgson et al, 1991;Ahlgren et al, 1992;Dunstan et al, 1993;Lombardi and Wangersky, 1995;Bell and Pond, 1996;Lo pez Alonso et al, 1998). On the other hand, nitrogen stress (Pohl and Zurheide, 1979;Shifrin and Chisholm, 1980;Parrish and Wangersky, 1987;A  lvarez Cobelas, 1989), and nutrient limitations in general (Reitan et al, 1994) have also been positively associated with increase in lipid abundance, although the response was species-speci®c (Shifrin and Chisholm, 1980;Lombardi and Wangersky, 1995).…”

Lipid class and carbohydrate concentrations in marine colloids

“…Nutrient availability greatly affects uic TAG con tent in algal cells Wangersky , 1987, 1990;Hodgson et al .. 1991).…”