CHEMICAL PROFILE OF SELECTED SPECIES OF MICROALGAE WITH EMPHASIS ON LIPIDS¹

Abstract

The lipid profile of seven species of unicellular eukaryotic microalgae grown under controlled conditions was studied with emphasis on the hydrocarbons and the fatty acids as part of a search for oil‐producing algae. Green, slow‐growing colonies of Botryococcus braunii Kutz contained the highest lipid content of 45% based on the organic weight, with an increase to 55% under nitrogen deficiency and with no effect of sodium chloride stress. Ankistrodesmus sp. Thomas, Dunaliella spp., Isochrysis sp., Nannochloris sp. Thomas, and Nitzschia sp. Chapman contained an average of 25% lipids under nitrogen sufficient conditions. Nitrogen deficiency resulted in significant increase in the lipid content in all species but Dunaliella spp., which produced a higher content of carbohydrates. Significant low amounts of acyclic hydrocarbons were detected only in Botryococcus braunii Kutz and not in the other algae. The major hydrocarbon fractions in nitrogen deficient Botryococcus braunii Kutz, Dunaliella salina Thomas, Isochrysis spp. and Nannochloris sp. Thomas were cyclic and branched polyunsaturated components which were identified as various isoprenoid derivatives. The polar lipid composition of glycolipids and phospholipids of all species investigated was fairly typical of photosynthetic eukaryotic algae. Fatty acid composition was species specific, with changes occurring in the relative amounts of individual acids of cells cultivated under different conditions and growth phases. All species synthesized C14:0, C16.0, C18:1, C18:2 and C18:3 fatty acids; C 16:4 in Ankistrodesmus sp. Thomas; C18:4 and C 22.6 in Isochrysis sp.; C16:2, C16:3 and C20:5 in Nannochloris sp. Thomas; C16:2, C16:3 and C20:5 in Nitzschia sp. Chapman. Nitrogen deficiency and salt stress induced accumulation of C18:1 in all treated species and to a lesser extent in Botryococcus braunii Kutz. The low production of hydrocarbons under optimal growth conditions and the high production of hydrocarbons under limited growth conditions cannot support the notion that microalgae can be utilized as biosolar energy converters for the production of liquid fuel, but point to the availability of a variety of neutral and polar lipid products.

Effects of UV radiation on five marine microphytobenthic Wadden sea diatoms, isolated from the Solthörn tidal flat (Lower Saxony, southern North Sea) – Part II: changes in carbohydrate, amino acid and fatty acid composition

“…Total soluble carbohydrates were determined using the phenol sulphuric acid method of Kochert (1978) and Ben-Amotz et al (1985), incorporating the modifications of Mercz (1994) and Buttery (2000). The samples were homogenized in 1 M H 2 SO 4 (if not otherwise mentioned, all of the chemicals used in this study were of the highest purity from Sigma-Aldrich) and, after heating at 100°C for 60 min, 0.3 ml of the supernatant was transferred into a fresh vial and made up to 2 ml with deionized water.…”

Protocol for maximizing the triglycerides-enriched lipids production from <i>Dunaliella salina</i> SA32007 biomass, isolated from the Salar de Atacama (Northern Chile)

“…Thus, the results represent the Percentage of total extractable lipids (%TELs) from fresh biomass of the microalgae. The Percentage of Triglycerides (%TAGs) in total extractable lipids was determined by the glycerol-3-phosphate-oxidase-p-chlorophenol enzymatic method (Triglyceride GOP/PAP AA from Wiener) using triolein as standard [10,28]. Each experimental result was obtained through a triplicated set of data.…”

“…The addition of these two adaptations includes, among others, changes in the expression of genes, the concentration of intracellular metabolites and the neutralization of toxic compounds in the new media [10,17,18]. As a consequence of this metabolic adjustment, normally, the algae suppress their reproduction and derive energy (as ATP) from the metabolic processes [19,28]. For Not Bubbled treatments, the lack of an external CO 2 source (Bubbling), inhibited the biomass increment of cultures, independently of the limitation in Nitrogen applied after or before the latent phase.…”

“…This behaviour could be the result of a biochemical response of microalgae to the shortage of a direct source of CO 2 , as reported by Mendoza and Molina, 2008 [10] in the case of the marine microalgae Crypthecodinium conil. This way, shortage of CO 2 would stimulate the microalgae to use alternative carbon sources, such as molecules from degradation of lipids, for their vital activities like as membrane building, plastid regeneration and photosynthesis [2,28,39]. The above mentioned observation is also sustained by the fact that, under stress conditions, lipids are the most abundant macromolecules because they prevent photooxidative stress [2,[40][41][42].…”

Analysis of Acetyl Co-A Carboxylase Activity in Marine Diatoms Isolated from Vellar Estuary, Southest Coast of India

“…The relative importance of altered partitioning of recently assimilated carbon and redistribution of earlier assimilated carbon from non-lipid compound into lipids in the lipid accumulation procedure has not been strongly established (Ben-Amtoz et al, 1985;Suen et al, 1987). The nature of lipid produced by silicon deficient diatoms has not been reported (Roessler, 1988), The research described in this paper represents intial efforts towards a determine the enzyme acetyl co-A carboxylase activity in marine diatoms Odontella aurita and Chaetoceros muelleri cultivated in different Si treatment nutrient medium to understanding the biochemistry of ACCase activity in different Si treatment diatoms.…”