Effects of medium salinity on growth and biochemical composition of the green microalga Tetraselmis suecica

Change in medium salinity due to evaporation or water addition is one of the significant factors affecting algal culture growth and biomass quality. This study evaluates the effect of different salinities on growth and lipid, protein, and carbohydrate content in the green alga Tetraselmis suecica. Four different concentrations (15 g L, 30 g L, 60 g L, 90 g L) of artificial sea salt were used to prepare f medium for the outdoor cultivation of T. suecica. The highest growth (up to 0.66 g L per day) was achieved using a medium with 15 g L salinity, and at higher concentrations of salts, biomass yields tend to be reduced. The highest carbohydrate content (16.1%) was obtained when cultivating T. suecica in a medium with 15 g L salinity. Protein content was significantly affected by the change in salinity, and it was found to be highest (56.9%) at 15 g L. Increasing salinity to 90 g L significantly reduced protein content. The highest lipid content (27.7%) was reached with biomass cultivated at 30 g L salinity, while further increase of salt concentration in the medium significantly reduced lipid content. Chlorophyll and total carotenoid content in the biomass varied from 2.8 to 5.5% and from 0.35 to 1.1%, respectively. Higher salinity resulted in a higher overall content of pigments (chlorophyll, carotenoids) but also a higher variation of concentration of these compounds during cultivation.