Thermal Stress Enhances Phenolic Metabolism and Antioxidant Capacity in Hamatococcus pluvialis: A Sustainable Platform for Microalgal Antioxidants
Résumé
Haematococcus pluvialis is a commercially valuable freshwater green microalga with the remarkable ability to produce abundant natural astaxanthin, a potent natural antioxidant with applications in nutraceuticals and cosmetics. Adverse cultivation conditions significantly affect the accumulation of phenolic compounds and antioxidant capacity in this microalga. In this study, the effects of three temperature treatments (10°C, 25°C, and 35°C) on antioxidant compounds accumulation in H. pluvialis were investigated using two culture media: BG11 and OHM. At 35°C, phenolic content per cell (0.104 ± 0.008 pgGAE/cell) and antioxidant capacity (0.005 ± 0.001 I%/cell) represented 1.8- and 2.5-fold increases, respectively, over 10°C values (p < 0.05, ANOVA). At 25°C, optimal growth conditions were observed, with the phenolic content and antioxidant capacity increasing proportionally with cell density. Notably, OHM medium supported significantly greater (p < 0.05) accumulation of antioxidant compounds compared to BG11. These findings confirm the biological value of H. pluvialis and highlight its potential applications in industrial and medical fields.