Light-Induced Changes in Fatty Acid Profiles of Specific Lipid Classes in Several Freshwater Phytoplankton Species

Abstract

We tested the influence of two light intensities [40 and 300 μmol PAR / (m2s)] on the fatty acid composition of three distinct lipid classes in four freshwater phytoplankton species. We chose species of different taxonomic classes in order to detect potentially similar reaction characteristics that might also be present in natural phytoplankton communities. From samples of the bacillariophyte Asterionella formosa, the chrysophyte Chromulina sp., the cryptophyte Cryptomonas ovata and the zygnematophyte Cosmarium botrytis we first separated glycolipids (monogalactosyldiacylglycerol, digalactosyldiacylglycerol, and sulfoquinovosyldiacylglycerol), phospholipids (phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, and phosphatidylserine) as well as non-polar lipids (triacylglycerols), before analyzing the fatty acid composition of each lipid class. High variation in the fatty acid composition existed among different species. Individual fatty acid compositions differed in their reaction to changing light intensities in the four species. Although no generalizations could be made for species across taxonomic classes, individual species showed clear but small responses in their ecologically-relevant omega-3 and omega-6 polyunsaturated fatty acids (PUFA) in terms of proportions and of per tissue carbon quotas. Knowledge on how lipids like fatty acids change with environmental or culture conditions is of great interest in ecological food web studies, aquaculture, and biotechnology, since algal lipids are the most important sources of omega-3 long-chain PUFA for aquatic and terrestrial consumers, including humans.

The lipid biochemistry of eukaryotic algae

“…Differences in how individual algae respond to light was also emphasised in a study of four freshwater phytoplankton species (including rarely examined Chrysophyceae and Zygnematophyceaea) under different light intensities. While there were significant changes in all algae examined, no generalisations about these alterations could be made [440].…”

Linking primary producer diversity and food quality effects on herbivores: A biochemical perspective

“…Lipids were extracted and transesterified into fatty acid methyl esters and then identified and quantified by gas chromatography (GC 6890 N, Network GC System, Agilent Technologies GmbH) according to Wacker et al . 33 . Sterols were extracted from GF/F filters loaded with aliquots of the algae cultures (1 mg C) and analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) as described in Martin-Creuzburg and Merkel 27 .…”

Diet tracing in ecology: Method comparison and selection

“…ALA to EPA) (Taipale, Kainz, & Brett, ). Trophic discrimination can vary for different resources, especially when diet components have substantially different fatty acid profiles than their consumers (Happel et al., ), and across different environmental conditions (Wacker, Piepho, Harwood, Guschina, & Arts, ). Consequently, accurate dietary categorisation of consumers relies on a priori estimates of calibration coefficients (Wang, Hollmén, & Iverson, ).…”