• ALGAE
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• v.24 no.2
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• pp.121-127
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• 2009

The unicellular green alga, Haematococcus pluvialis, accumulates the highest level of astaxanthin among knownastaxanthi.n-producing organisms. Light is the most important factor to induce astaxanthin by H. pluvialis. BIue andred LEDs, whose ${\lambda}_{max}$'s are 470 and 665 nm, respectively, were used for internally illuminated light sources.Fluorescent lamps were also used for both internal and external illumination sources. The astaxanthin levels in thesevarious lighting systems were analyzed and compared each other. The cultures under internally illuminated LEDsaccumulaled 20% more astaxanthin than those under fluorescent lamp. Furthermore, LEDs generated much lessheat than the fluorescent lamps, which gives one more reason for the LEDs being a suitable internal Light source forastaxanthin induction. The results reported here would lead novel designs of photobioreactors with improvementsof illumination methods for high level of astaxanthm production. The maximum astaxanthin concentrations as wellas the astaxanthin yield per supplied photon were increased by at least 20% when blue or red LEDs were supplied.