Salinity as an Abiotic Stressor for Eliciting Bioactive Compounds in Marine Microalgae.

This study investigated the impact of culture medium salinity (5-50 PSU) on the growth and maximum photochemical yield of photosystem II (/) and the composition of carotenoids, fatty acids, and bioactive substances in three marine microalgae (, , and ). The microalgae were photoautotrophically cultured in discontinuous mode in a single stage (S1) and a two-stage culture with salt shock (S2). A growth model was developed to link biomass productivity with salinity for each species. achieved a maximum biomass productivity () of 15.85 ± 0.32 mg·L·day in S1 and 16.12 ± 0.13 mg·L·day in S2. The salt shock in S2 notably enhanced carotenoid production, particularly in and , where fucoxanthin was the main carotenoid, while peridinin dominated in . also exhibited increased fatty acid productivity in S2. Salinity changes affected the proportions of saturated, monounsaturated, and polyunsaturated fatty acids in all three species. Additionally, hyposaline conditions boosted the production of haemolytic substances in and