초록
Microalga Haematococcus pluvialis is reported as a large producer of carotenoid. One of the carotenoids produced by the microalgae is astaxanthin that can be used as antioxidant. The astaxanthin is known as ''the king of antioxidant'', reportedly 800 times stronger than Coenzyme Q10 (CoQ10), 75 times stronger than Alpha Lipoic Acid (ALA) and 6000 times stronger than Vitamin C. Research has discovered that astaxanthin absorbs more free radicals than any other antioxidants. It is also indicated for sun protection, exercising recovery and eye health. However, under normal condition, carotenoid and biomass of the microalgae are very low. Light stress treatment is reportedly able to enhance carotenoids in plants and presumably in microalgae. Therefore, this research aims to increase carotenoid and biomass of the microalga by using the combination of blue, red, and white with ultraviolet lights. The microalga H.pluvialis was cultured in Bold Basal medium for 14 days under irradiation of blue, red and white lamp (1500 lux) for 21hours and irradiation of ultraviolet light (500 lux) for 3hours. As a control, the microalga wascultured in Bold Basal medium under irradiation of white lamp (1500 lux) for 12:12hours (dark and light cycle). Each treatment and control was repeated for three times. Its parameters were cell number, chlorophyll and carotenoid content. The number of cells was counted by Haemacytometer Neubauer 1mm and chlorophyll, and carotenoids content were analyzed by spectrophotometry at absorbance of 700, 663, 645, and 478nm. The combination of ultraviolet and blue light was the best treatment for increasing the total carotenoid and chlorophyll content since the total carotenoid content increased about 8 times of the control and the total chlorophyll content increased about 2 times of the control, they accounted for 5,1mg / L and 6,55mg / L, respectively. Meanwhile, the combination of ultraviolet and red light increased its biomass up to 1.4 x 10<SUP>4</SUP>cell /ml which was about 2 times of the control.