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- Effects of phosphorus-induced changes on the growth, nitrogen uptake, and biochemical composition of Pavlova pinguis and Hemiselmis cf. anderseniiPublication . Fernandes, Tomásia; Cordeiro, NereidaThe understanding of the phosphorus-induced changes in the biochemical composition of microalgae is of great importance for achieving efciency in high-value lipid production. To study the chemoplasticity of Pavlova pinguis (Haptophyceae) and Hemiselmis cf. andersenii (Cryptophyceae), their growth, carotenoid and chlorophyll a content, and their monosaccharide and lipid profles were analyzed against several phosphorus (P) regimes: low (LP), medium (MP), and high (HP). For both microalgal cultures, increasing initial P concentrations showed a positive efect on biomass productivities. Carbon-rich pools presented signifcant diferences (p<0.05) for P. pinguis against P treatments, in contrast to H. cf. andersenii. Diferential responses to P-induced changes in microalgae monosaccharide and lipid profle were observed. Hemiselmis cf. andersenii increased its proportion in galactose (up to 3 times) from LP to HP conditions, whereas P. pinguis decreased (up to 20%) its glucose proportion from LP to HP conditions. For P. pinguis, the lowest amount (13.12 mg g−1 dw) of sterols was observed at LP conditions, in contrast to its carotenoid content (4.32 mg g−1 dw). P-replete conditions were the most efective in induc ing high-value lipid accumulation. Non-targeted lipid analysis revealed which samples would need to be processed to fully exploit its high-value lipids, namely H. cf andersenii under MP and HP conditions. This study demonstrated that P played an important role in carbon allocation, nitrogen uptake, and lipid regulation on P. pinguis and H. cf. andersenii, and that P-replete conditions could be useful for optimizing high-value lipids with potential for nutraceutical and pharmaceutical felds.
- High-value lipids accumulation by Pavlova pinguis as a response to nitrogen-induced changesPublication . Fernandes, Tomásia; Cordeiro, NereidaThe challenges of exploring the potential of microalgal strains for biotechnological applications include the optimization of their cell growth and chemical composition. To overcome this, it is essential to understand the mechanisms that lead to the accumulation of desired products within microalgal cells. In this study, a gradient of nitrogen as nitrate (NO−3 − N) concentrations was used for the preparation of P. pinguis growth medium. The algal growth dynamics, pigments, nutrient uptake, and detailed lipid composition across treatments were assessed. Increasing the NO− 3 − N level led to higher lipid content (21%), a higher cell uptake rate (0.20 pg NO− 3 − N cell− 1 d− 1 ) and more accumulation of chlorophylls, carotenoids, and high-value lipids. Eicosapentaenoic acid, essential fatty acids, phytol and stigmasterol were the key high-value lipids that were positively influenced by higher NO− 3 − N levels. High NO− 3 − N conditions induced an increase of 54% in total sterol content, while low NO− 3 − N conditions resulted in increased proportions of saturated fatty acids (66% more) and decreased proportions of polyunsaturated fatty acids (14% less). The low NO− 3 − N level also led to higher amounts of monoglyceride (1.60 mg g− 1 ; 64% more). The analysis of P. pinguis lipids before and after hydrolysis provided an insight into the composition of the esterified lipids across treatments. NO− 3 − N supplementation was revealed to be an effective strategy for enhancing P. pinguis lipid composition, for nutraceutical and pharmaceutical industries (high NO− 3 − N level). A greater understanding of the NO− 3 − N uptake and the use efficiency by P. pinguis was reached, showing its potential for further biotechnological applications.
- Exploring Pavlova pinguis chemical diversity: a potentially novel source of high value compoundsPublication . Fernandes, Tomásia; Martel, Antera; Cordeiro, NereidaTo uncover the potential of Pavlova pinguis J.C. Green as a natural source of value added compounds, its lipophilic extracts were studied before and after alkaline hydrolysis using gas chromatography-mass spectrometry (GC-MS). The GC-MS analysis of the lipophilic extracts showed a wide chemical diversity including 72 compounds distributed by fatty acids (29), sterols (14), fatty alcohols (13) and other lipophilic compounds (16). Fatty acids represented the main class of identified compounds presenting myristic, palmitic, palmitoleic and eicosapentaenoic acids as its main components. Through the ∑ω6/∑ω3 ratio (0.25) and sterol composition it was possible to observe that P. pinguis is a valuable source of ω3 fatty acids and stigmasterol (up to 43% of total sterols). After alkaline hydrolysis, fatty acids and fatty alcohols content increased by 32 and 14% respectively, in contrast to, monoglycerides which decreased by 84%. The long chain alcohols content enables the exploitation of this microalga as a source of these bioactive compounds. Smaller amounts of sugars and other compounds were also detected. The present study is a valuable reference to the metabolite characterization of P. pinguis and shows the potential of this microalga for nutraceutical and pharmaceutical industries.