Microalgae Haemococcus pluvialis, Cultured in OHM Medium under Stressful Conditions: Phenolic Content and Antioxidant Capacity

Haematococcus pluvialis, a unicellular green microalgae, is able to accumulate the large amounts of astaxathin under stress conditions. Nutritional factors such as nitrate or phosphate and light intensity play an important role in the growth, accumulation of phenolic compounds and antioxidant capacity microalgae H. pluvialis. In this study, H. pluvialis was cultured under three conditions of stress, nutrient depletion, denitrification of nitrate and addition of NPK fertilizer, and natural light in OHM medium to investigate the phenolic content and antioxidant capacity of the biomass of H. pluvialis microalgae. The results showed that, under denitrification of nitrate and addition of NPK fertilizer, the phenolic content reached a high value (8.054 µg gallic acid/g) and there was no significant difference with the two conditions of nutrient depletion (4.115 µg gallic acid/g) and natural light (4.707 µg gallic acid/g) (p<0.05). However, no differences were found between the antioxidant capacity under denitrification of nitrate and addition of NPK fertilizer (51.390%) and natural light (52.301%) (p=0.552) that were higher than nutrient depletion (45.257%) (p<0.05). Thus, under the stress conditions of nitrate depletion and high light intensity, H. pluvialis has the ability to synthesize and accumulate high amounts of bioactive compounds and microalgae biomass can be applied in dietary supplement and cosmeticeuticals.