Abstract:

This study aims to explore the effects of initial pH of culture medium and different illumination wavelengths on
the contents of carotenoids including β-carotene and lutein from Dunaliella salina during culture. In experiments, media
with different pH values were prepared and used to culture Dunaliella salina for 105 days. Under the illumination of white
(full wavelengths), red (630 nm) and blue light (430 nm), medium with pH 7 was applied to culture Dunaliella salina for
40 days. Dunaliella salina culture density was then determined while β-carotene and lutein contents were assessed from
culture liquid. Data obtained from the experiments suggested that: 1) Dunaliella salina was able to adjust the environmental
pH to neutral. After 105-day culture, an increased Dunaliella salina culture density was observed from culture liquids with
original pH 10–13, pH 1–3 and pH 4–9 while the maximum Dunaliella salina culture density was counted at pH 4 (1 851 cell
counts/mL). Higher β-carotene (0.489-0.561 mg/mL) and lutein (0.610-0.700 mg/mL) contents were observed from culture liquids
with original medium pH 7–9, while higher β-carotene (0.603-0.730 ng) and lutein (0.897-0.979 ng) contents were seen from
single cells with original medium pH 11-13; 2) Dunaliella salina culture density could increase under illumination at the full-range
wavelength, red (630 nm) and blue light (430 nm) after 40-day culture. Both red and blue lights were able to induce increased
contents of β-carotene (0.589 ng) and lutein (0.524 ng) from single cells while blue light was the most effective.

Key words: Dunaliella salina, carotenoid, lutein, β-carotene