In addition to characteristic fatty acid methyl esters (FAMEs), biodiesel produced from Isochrysis sp. contains a significant amount (14%, w/w) of predominantly C37 and C38 long-chain alkenones. These compounds are members of a class of lipids known collectively as polyunsaturated long-chain alkenones (PULCAs) that are produced by a range of other prymnesiophyte taxa. The physical properties of alkenones, such as high melting points (∼60 °C), renders the direct product unsuitable for use as a diesel fuel but, nonetheless, represents an important and as yet unexplored renewable carbon feedstock.

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Nannochloropsis salina was cultured batch-wise to evaluate the potential of the alga to produce biodiesel. The cells were harvested at the end of the exponential growth phase when the concentration was 18 · 106 cells/mL culture. The growth estimated as dry weight from this cell number was (3.8 ± 0.7) mg/L. The lipid and triglyceride contents were 40% and 12% on a dry weight basis, respectively. The amount of the ratio triglycerides/total lipids was approximately 0.3.The composition of triglyceride fatty acid methyl esters (biodiesel) was analysed by gasliquid chromatography and identified as: C14:0, C16:0, C16:1, C18:0, C18:1, C18:2, C18:3, C20:1, and C20:5. The ratio of unsaturated to saturated fatty acid contents was approximately 4.4. Additionally, the characterization of each individual fatty acid ester was discussed with regard to the fuel properties of biodiesel produced by the alga.