FATTY ACID CONTENT AND CHEMICAL COMPOSITION OF FRESHWATER MICROALGAE¹

Abstract

Fatty acid (FA), total lipid, protein, amino acid, carbon, nitrogen, and phosphorus content was analyzed in 24 samples of freshwater microalgae. The samples originated from batch, continuous, or mass cultures in various growth phases and from net samples from lakewater. FA were analyzed quantitatively by using an internal standard in a GLC system and expressed as mg·g−1 dry weight (DW). The FA of one group of blue‐greens (e.g. Oscillatoria and Microcystis) were similar to those of the greens with higher amounts of 18C acids of the ω3 type compared to the ω6 type, whereas the other group (e.g. Anabaena and Spirulina) contained mostly ω6 acids. The flagellates, a taxonomically diverse group, were characterized by high amounts of long‐chained (20–22 C) polyunsaturated FA (PUFA), particularly of the ω3 type. The ω3/ω6 ratio appears to be highest in algae in the exponential growth phase. The increased lipid content in stressed algae was mostly due to increased saturated fatty acids and ω6 acids, whereas the valuable ω3 acids were unchanged or even decreased. Amino acid composition (% of total amino acids) did not vary much betaken species, but when analyzed quantitatively (mg‐g−1 DW), varied considerably between species and within species in different growth phases. The nitrogen and phosphorus contents were variable in all three algal groups. The relationship between PUFA and phosphorus content differed among the algal groups. The data suggest that PUFA in the phospholipids consist mostly ω3 acids.

Biomarkers as organic-carbon-source and environmental indicators in the Late Quaternary Arctic Ocean: problems and perspectives

“…Volcani, 1966;Kattner, 1993 , marine Ž Dinophyceae Mayzand et al, 1976;Fraser et al, . 1989;Ahlgren et al, 1992 , as well as Haptophyceae Ž . Sargent et al, 1985, Conte et al, 1994 .…”

“…Sargent et al, 1985, Conte et al, 1994 . Shortchain fatty acids, however, are also found in lacus-Ž trinerfreshwater environments Ahlgren et al, 1992; . Leveille et al, 1997 .…”

“…Ahlgren et al, 1992;Leveille et al, 1997 .T he relative abundances of 4a-23,24-trimethyl-Ž . 5a-cholest-22 E-en-3b-ol dinosterol and 24-meth-Ž .…”

Carbon and nitrogen cycling on intertidal mudflats of a temperate Australian estuary. III. Sources of organic matter

“…and had a measured ratio to chl a of 0.3 (Table 5). It was assumed that the contribution of 18:4 by chlorophytes (which are known to produce C 18 65 PUFAs) was negligible, since previous studies have shown that chlorophytes only produce small amounts of 18:4 compared to total lipids (~3%) (Volkman et al 1989, Ahlgren et al 1992). These 2 approaches were generally in broad agreement ( Table 6), suggesting that Oscillatoria spp.…”

Estimation of Amino Acid Quality of Food for Benthic Invertebrates and Fish on the Basis of Comparative Study of Amino Acids of Periphyton and Zoobenthos of the Yenisey River

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