Carotenogenic Activity of Two Hypersaline Greek Dunaliella salina Strains under Nitrogen Deprivation and Salinity Stress

The culture growth and carotenogenic activity of two Greek Dunaliella salina strains (AthU-Al D30 and AthU-Al D31) under stress conditions are investigated herein, with emphasis on β-carotene production as well as on lutein and zeaxanthin. In particular, the strains were cultivated in “standard” conditions (60 ‰ salinity and 1.18 M of NaNO3), under salinity stress conditions (160 ‰ salinity and 1.18 M of NaNO3) and under nitrogen deprivation conditions (60 ‰ salinity and 0 M of NaNO3). In addition to the two Greek strains, the D. salina CCAP 19/18 strain, which has been extensively studied regarding carotenogenesis, is included in this study as a reference. All three strains were found to produce increased amounts of β-carotene when cultivated under nitrogen deprivation conditions, while the AthU-Al D31 strain also produced high amounts of carotenoids under salt stress. The HPLC carotenoid profiles of the strains revealed reduced production of lutein in nitrogen deprivation conditions, coupled with a high production of β-carotene. The strains exhibited various responses in terms of carotenogenic activity, indicating an intraspecific variation in the metabolic reactions related to carotenogenesis.