shows the specific growth rate, dry-cell weight,
specific maximum production rate of astaxanthin and astaxanthin
concentration in fermentation broth after 8 days under
illumination at 2.8mol-photonm−2 s−1 with LEDs emitting
different wavelengths and the fluorescent lamp. High
cell and astaxanthin concentrations were obtained under illumination
with LEDs emitting shorter wavelengths. The
fluorescent lamp shows a low intensity of emission in this
range and thus was ineffective for growth of cells and astaxanthin
production. Green LEDs (λmax = 525 nm) were
also ineffective for growth of cells, because the absorption
efficiency of chlorophyll in this range of wavelength is low.
The effectiveness of illumination at 380–470 nm for astaxanthin
production was confirmed by the fact that the color
of these fermentation broths changed from green to red at
4–5 days, while the broth illuminated with red LEDs or the
fluorescent lamp remained brownish green.