To further examine the effectiveness of blue and red
light on astaxanthin accumulation, cells were also cultivated
under low intensities of internal light without
external illumination. Three PBRs were setup with only
internal light sources with the intensity of 20 μE m–2 s–1
(Table 2). The light intensity of 20 μE m–2 s–1 was not
enough to support the high density culture or to fully
induce astaxanthin. The cell didn’t grow very well in all
three cases (refer Fig. 4a) and the astaxanthin concentration
did not increase till day 15 (refer Fig. 4b). The astaxanthin
level, however, started to increase to a certain