Effect of Melatonin as a Bio-stimulant of Astaxanthin Production from Haematococcus

To enhance productivity of microalgae Haematococcus as an only one producer from nature of anti-oxidative pigment of astaxanthin, effect of melatonin to biomass growth and astaxanthin production from Haematococcus lacustris was investigated under abiotic stress culture conditions of different light intensities. Biomass and astaxanthin production were enhanced to 11% and 25%, respectively with the addition of 1.0 mg L-1 of melatonin at initial stage of cultivation under high light intensity. Lower concentration of melatonin was effective for growth promotion by improving stress tolerance while higher concentration of melatonin exhibited growth inhibition. Melatonin could be categorized as a bio-stimulant since it was effective at significantly lower dosage compared to other types of additives.