Fucoxanthin and xanthophyll-cycle pigment dynamics during two-phase cultivation of five marine microalgae under different nitrogen sources supplementation

Abstract Fucoxanthin is an algal carotenoid of increasing commercial interest due to its potent antioxidant, anti-inflammatory, and diverse health properties. Its applications ranged from the aquaculture industry, where it can enhance pigmentation, immunity, to nutraceutical sector, as a functional ingredient. This study evaluated the accumulation of fucoxanthin and the xanthophylls cycle pigment dynamics of five microalgae species Pavlova gyrans , Heterosigma akashiwo , Gephyrocapsa huxleyi (former Emiliania huxleyi) , Isochrysis galbana and Phaeodactylum tricornutum . The strains were grown in F/2 medium enriched with two isonitrogenous supplementation strategies (24 mg L −1 nitrogen) based on urea and sodium nitrate. A two-phase light regime was applied: 10 days under high light intensity followed by an 8 days low-light phase. Fucoxanthin and other xanthophylls were quantified by HPLC. Interspecific differences were observed regarding the five strains: I. galbana and P. tricornutum showed the highest fucoxanthin productivities, ranging between 0.074 – 0.085 and 0.051 – 0.067 mg L −1 day −1 , respectively. Intermediate productivities were obtained in H. akashiwo and P. gyrans , while G. huxleyi displayed the lowest fucoxanthin productivity, up to 0.043 mg L −1 day −1 . Interestingly, considering fucoxanthin derivates (PULL – FX) content, the highest concentration was found in G. huxleyi , ranging 0.841 – 0.896 mg g −1 . Differences among nitrogen sources were detected only in P. gyrans , which increased its fucoxanthin’s content more than a 40% under urea regime. This study highlights the exploration of new strains for fucoxanthin production based on the xanthophylls cycle dynamic and photoacclimation responses. Overall, I. galbana and P. tricornutum were positioned as the most promising candidates for fucoxanthin production.