Comparing EPA production and fatty acid profiles of three Phaeodactylum tricornutum strains under western Norwegian climate conditions

Pia Steinrücken; Siv Kristin Prestegard; Jeroen Hendrik de Vree; Julia E Storesund; Bernadette Pree; Svein Are Mjøs; Svein Rune Erga

doi:10.1016/j.algal.2017.12.001

Comparing EPA production and fatty acid profiles of three Phaeodactylum tricornutum strains under western Norwegian climate conditions

Algal Res. 2018 Mar:30:11-22. doi: 10.1016/j.algal.2017.12.001.

Authors

Pia Steinrücken¹, Siv Kristin Prestegard², Jeroen Hendrik de Vree¹, Julia E Storesund¹, Bernadette Pree¹, Svein Are Mjøs³, Svein Rune Erga¹

Affiliations

¹ Department of Biology, University of Bergen, PO Box 7803, N-5020 Bergen, Norway.
² Applied Biotechnology, Uni Research Environment, Nygårdsgaten 112, N-5006 Bergen, Norway.
³ Department of Chemistry, University of Bergen, Allégaten 42, N-5020 Bergen, Norway.

Abstract

Microalgae could provide a sustainable alternative to fish oil as a source for the omega-3 polyunsaturated fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). However, growing microalgae on a large-scale is still more cost-intensive than fish oil production, and outdoor productivities vary greatly with reactor type, geographic location, climate conditions and microalgae species or even strains. The diatom Phaeodactylum tricornutum has been intensively investigated for its potential in large-scale production, due to its robustness and comparatively high growth rates and EPA content. Yet, most research have been performed in southern countries and with a single commercial P. tricornutum strain, while information about productivities at higher latitudes and of local strains is scarce. We examined the potential of the climate conditions in Bergen, western Norway for outdoor cultivation of P. tricornutum in flat panel photobioreactors and cultivated three different strains simultaneously, one commercial strain from Spain (Fito) and two local isolates (M28 and B58), to assess and compare their biomass and EPA productivities, and fatty acid (FA) profiles. The three strains possessed similar biomass productivities (average volumetric productivities of 0.20, 0.18, and 0.21 g L^{- 1} d^{- 1}), that were lower compared to productivities reported from southern latitudes. However, EPA productivities differed between the strains (average volumetric productivities of 9.8, 5.7 and 6.9 mg L^{- 1} d^{- 1}), due to differing EPA contents (average of 4.4, 3.2 and 3.1% of dry weight), and were comparable to results from Italy. The EPA content of strain Fito of 4.4% is higher than earlier reported for P. tricornutum (2.6-3.1%) and was only apparent under outdoor conditions. A principal component analysis (PCA) of the relative FA composition revealed strain-specific profiles. However, including data from laboratory experiments, revealed more significant differences between outdoor and laboratory-grown cultures than between the strains, and higher EPA contents in outdoor grown cultures.