Abstract:
Vegetative Haematococcus pluvialis NIESS144 was investigated for their astaxanthin production. The determination of suitable conditions for the induction of astaxanthin was achieved in 1.5L bubble column photobioreactor. Parameters of interest included nutrient concentration (diluted 5X, 10X, 15X spent medium concentration), initial cell concentrations (diluted 10X, 20X, 25X initial cell concentration), light intensity and mode of illumination (indoor/outdoor). Outdoor experiments were subject to illumination at the light intensity range of 70-150 klux whereas Indoor experiments were with light intensities of 0.65, 2.73, 4.83 and 6.5 klux. Under outdoor condition, the maximum astaxanthin of 2.24% dry weight was found at 10X spent medium dilution after 14 days. Diluting initial cell concentration at outdoor condition could only produce, after 14 days, 1.56% by weight astaxanthin at 10X dilution of the final harvested cell concentration. For indoor experiments, fluorescent lamps were used as a light source. The maximum astaxanthin from indoor conditions was 5.39% by weight (dry) after 8 days at 10X dilution of the final harvested cell concentration and 6.5 klux light intensity whereas the dilution of spent medium concentration (10X) could only reach the maximum of 3.81% after 6 days at 6.5 klux. Induction in the 2.7L airlift photobioreactor was carried out at 10X dilution of the final spent medium concentration, 10X dilution of the final harvested cell concentration and 6.5 klux light intensity. The aeration was supplied to the airlift at the same rate as that in the bubble column photobioreactor (20 cm3/s). Astaxanthin at 2.16% dry weight was obtained in this airlift system after 16 days of operation. Simple economical calculation suggested that the most feasible condition was at 25X dilution of the final harvested cell concentration with the light intensity of 2.73 klux.
