Microalgae as Sustainable Bio-Factories of Healthy Lipids: Evaluating Fatty Acid Content and Antioxidant Activity

Abstract

The demand for sustainable and environmentally friendly food sources and food ingredients is increasing, and microalgae are promoted as a sustainable source of essential and bioactive lipids, with high levels of omega-3 fatty acids (ω-3 FA), comparable to those of fish. However, most FA screening studies on algae are scattered or use different methodologies, preventing a true comparison of its content between microalgae. In this work, we used gas-chromatography mass-spectrometry (GC-MS) to characterize the FA profile of seven different commercial microalgae with biotechnological applications (Chlorella vulgaris, Chlorococcum amblystomatis, Scenedesmus obliquus, Tetraselmis chui, Phaeodactylum tricornutum, Spirulina sp., and Nannochloropsis oceanica). Screening for antioxidant activity was also performed to understand the relationship between FA profile and bioactivity. Microalgae exhibited specific FA profiles with a different composition, namely in the ω-3 FA profile, but with species of the same phylum showing similar tendencies. The different lipid extracts showed similar antioxidant activities, but with a low activity of the extracts of Nannochloropsis oceanica. Overall, this study provides a direct comparison of FA profiles between microalgae species, supporting the role of these species as alternative, sustainable, and healthy sources of essential lipids.

Keywords: GC-MS; fatty acids; lipidomics; lipids; mass spectrometry; microalgae.

Figure 1

Lipid content of Chlorella vulgaris, Chlorococcum amblystomatis, Scenedesmus obliquus, Tetraselmis chui, Phaeodactylum tricornutum, Spirulina sp., and Nannochloropsis oceanica (expressed in percentage % of biomass). Matching letters (a–f) indicate statistically significant differences between microalgae species, i.e., the same letter represents significant differences (q < 0.05, Kruskal–Wallis test followed by Dunn’s post-hoc comparisons).

Figure 2

(A) Principal component analysis (PCA) scores plot and (B) Boxplots of the 6 major contributors for PC1 using the relative abundance after log normalization of all fatty acids identified in Chlorella vulgaris, Chlorococcum amblystomatis, Scenedesmus obliquus, Tetraselmis chui, Phaeodactylum tricornutum, Spirulina sp., and Nannochloropsis oceanica. Abbreviations: C, Chlorococcum amblystomatis; C.v, Chlorella vulgaris; SC, Scenedesmus obliquus; T.C, Tetraselmis chui; Phae, Phaeodactylum tricornutum; SP, Spirulina sp.; and N.O, Nannochloropsis oceanica. Matching letters (a–s) indicate statistically significant differences between microalgae species, i.e., the same letter represents significant differences (q < 0.05, Kruskal–Wallis test followed by Dunn’s post-hoc comparisons).

Figure 3

Evaluation of the antioxidant activity of lipid extracts from different microalgae. Concentration of lipid extract (µg.mL⁻¹) that provided: (A) 50% inhibition of the ABTS^●+ radical, (B) 20% inhibition of the DPPH^● radical, and (C,D) the Trolox equivalents (TE; µmol.g⁻¹). The values are displayed as the mean (n = 3) ± standard deviation. Matching letters (a–c) represent significant differences between microalgae, i.e., the same letter represents significant differences (q < 0.05, Kruskal–Wallis test followed by Dunn’s post-hoc comparisons).