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Microalgae produce a variety of high-value chemicals including carotenoids. Fucoxanthin is also a carotenoid that has many physiological functions and biological properties. For this reason, the cost-effective production of fucoxanthin at an industrial scale has gained significant attention. In the proposed study, fucoxanthin production was aimed to be increased by altering the culture conditions of N. shiloi. The effect of light intensity aeration rate, different nitrogen sources, and oxidative stress on the biomass and fucoxanthin productivity have been discussed. Based on these results, the fucoxanthin increased to 97.45 ± 2.64 mg/g by adjusting the light intensity to 50 µmol/m2s, and aeration rate at 5 L/min using oxidative stress through the addition of 0.1 mM H2O2 and 0.1 mM NaOCl to the culture medium. Fucoxanthin was then purified with preparative HPLC using C30 carotenoid column (10 mm × 250 mm, 5 μm). After the purification procedure, Liquid chromatography tandem mass spectrometry (LC–MS/MS) and UV-vis spectroscopy were employed for the confirmation of fucoxanthin. This study presented a protocol for obtaining and purifying considerable amounts of biomass and fucoxanthin from diatom by manipulating culture conditions. With the developed methodology, N. shiloi could be evaluated as a promising source of fucoxanthin at the industrial scale for food, feed, cosmetic, and pharmaceutical industries. [ABSTRACT FROM AUTHOR]

Microalgae with high growth rates represent a potential source of carotenoids including fucoxanthin. For commercial fucoxanthin production, choosing the cultivation system is a critical parameter where the final biomass must contain a high content of the target product. To realize this, the reaction system must allow the use of stress conditions that induce the synthesis of these compounds. In this study, oxidative stress was applied to the diatom Amphora capitellata by the formation of reactive oxygen species in the culture medium through chemical reactions which generate. The effect of this oxidative stress on the amount of fucoxanthin and specific growth rate of A. capitellata was investigated. In the presence of H2O2/NaOCl, fucoxanthin content was 41.83 ± 0.92 mg g−1 as determined by HPLC–DAD a 2.20-fold increase compared with the control group. For the purification of fucoxanthin, preparative HPLC using a semi-prep C30 carotenoid column (10 × 250 mm, 5 µm) was used for the first time with an isocratic elution of 75:25 (methanol:acetonitrile) mobile phase at a flow rate of 4 mL min−1. Liquid chromatography tandem mass spectrometry (LC–MS/MS) was employed for the confirmation of fucoxanthin. The developed method has potential to obtain highly pure fucoxanthin for food and pharmaceutical applications using A. capitellata as a commercial source of fucoxanthin, particularly after its enhancement via oxidative stress. [ABSTRACT FROM AUTHOR]