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.
The intention of the study was to investigate the effect of physical conditions such as aeration rate (1, 3, 5 L/min) as well as chemical conditions including sodium nitrite (NaNO2), urea (CH4N2O) and ammonium chloride (NH4Cl) on the biomass productivity and fucoxanthin concentration of A. capitellata. The optimum cultures were cultivated in f/2 medium using sodium nitrate (NaNO3) at the light intensity of 100 µmol photons/ m2s with aeration rate of 2 L/min in 2 L bubbling bottle photobioreactors. These were then incubated at 22.0±2 °C, under the light intensities of 300 µmol photons/ m2s with three different airflow rates of 1, 3, 5 L/min for 16 days. And then, culture medium was prepared with three different nitrogen sources to achieve higher biomass productivity. During the production of A. capitellata, the maximum specific growth rate of 0.166 day-1, which corresponded to the doubling time 4.166 day, was obtained at the light intensity of 300 µmol photons/ m2s with aeration rate of 1 L/min when sodium nitrate was used. Chlorophyll-a and fucoxanthin contents were also at the highest level in the same light intensity. Dry biomass amount reached the maximum level of 0.66±0.17 g/L in case of NaNO2. In this study, it was identified that the aeration rate of 1 L/min, the light intensity of 300 µmol photons/m2s and sodium nitrate (NaNO3) were the optimum value for the growth of A. capitellata cells and production of biomass and fucoxanthin concentration.
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