Biochemical and Antioxidant Responses of Dunaliella salina to Thermal and Nutrient Stress

Dunaliella salina is a halophilic green microalga belonging to the genus Dunaliella of the phylum Chlorophyta, widely recognized as a premier natural source of high-value metabolites, particularly carotenoids and lipids, due to its remarkable adaptability to extreme environments. In this study, the microalgal strain D. salina CCAP 19/18 was utilized to investigate the accumulation of carotenoids, lipids, phenolics, as well as estimation of antioxidant capacity, under the induction of various thermal regimes and nutrient (NPK) stress. The results demonstrated that D. salina microalgae enhanced the synthesis of carotenoids, lipids, phenolic compounds and alongside increased antioxidant capacity under the stimulation of thermal and nutrient (NPK) stress. These metabolite contents reached peak levels at temperatures ranging from 10 to 25 oC across all nutrient (NPK) stress. Conversely, high temperature stress at 45oC proved unsuitable for both growth and metabolite accumulation in D. salina microalgae. Consequently, thermal and nutrient (NPK) stress were identified as key factors in inducing the synthesis of bioactive compounds in D. salina microalgae.