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

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.

An Overview of Potential Oleaginous Microorganisms and Their Role in Biodiesel and Omega-3 Fatty Acid-Based Industries

“…The diatom Phaeodactylum tricornutum is photoautotrophic in nature, while it can be grown in mixotrophic conditions, allowing photoautotrophic as well as heterotrophic cultivation conditions simultaneously, although, in this case, glucose utilization requires light [158][159][160][161][162][163][164][165][166][167]. When glucose transporters were introduced through genetic engineering, P. tricornutum could grow heterotrophically on various carbon sources in the dark [166,168].…”

High Resolution Proteome of Lipid Droplets Isolated from the Pennate Diatom Phaeodactylum tricornutum (Bacillariophyceae) Strain pt4 provides mechanistic insights into complex intracellular coordination during nitrogen deprivation

“…Furthermore, our preliminary observations suggested that Pt4 appeared to have higher yields of LDs from cells disrupted by hypotonic shock, perhaps because they are more amenable to this particular cell disruption method, and potentially related to differences in membrane lipid composition (Steinrücken et al. 2018) or owing to differences in their environments of origin (Martino et al. 2007).…”

Microalgae biotechnology in Nordic countries – the potential of local strains

“…Two strains of the diatom P. tricornutum and one strain of Attheya septentrionalis showed high growth rates (≥ 0.7 divisions day −1 ) and increased EPA content in laboratory scale experiments (Table ). When the two local strains of P. tricornutum were grown outdoors, in flat panel photobioreactors, during a 6 months period (May–October) they were outperformed in terms of EPA production by a commercial strain of P. tricornutum (Steinrücken et al ). Moreover, outdoor vs indoor (laboratory) cultivation had a profound effect on the fatty acid composition.…”