The photosynthetic microalga Haematococcus pluvialis, a potential source of astaxanthin, was cultivated under illumination with LEDs emitting red (λmax= 625 nm), green (λmax= 525 nm), blue (λmax= 470 nm), blue-purple (λmax= 410 nm) and purple (λmax= 380 nm) light and a fluorescent lamp, and the effects of wavelength on cell growth and astaxanthin accumulation were studied. LEDs emitting light of short wavelengths (380 -470 nm) were found to induce astaxanthin accumulation of up to 5 -6% per dry-cell, although the induction caused the suppression of cell growth. From these results, we proposed a new strategy of cultivating H. pluvialis under illumination with red LEDs without inducing a high level of astaxanthin accumulation, and then switching to illumination with blue LEDs at a high light intensity to induce a high level of astaxanthin accumulation.

No abstract

No abstract

No abstract

In order to increase the cell concentration and the accumulation of astaxanthin, the effects of nutrient concentration, pH, illumination and methods of supplying nutrients were studied for the cultivation of Haematococcus pluvialis. The replacement of media to avoid the deficiency of nutrients increased the cell concentration above 1 mg-dry cell cm(-3) without induction of astaxanthin accumulation. Illumination with blue light emitting diode lamps and nutrient starvation induced accumulation of astaxanthin, and the interactive effects of these two increased the astaxanthin concentration to 76 mug cm(-3).