2.3. Second stage culture
The photoautotrophic culture with basic nutrition (first stage) was stopped after cell density reached the early stationary phase. Cells were harvested by centrifugation (994 g, 15 min) and residual medium was removed. Collected cells were washed thoroughly with distilled water. Cells were transferred to f/2 medium with optimal salt concentrations, resuspended, and cultured under
second stage conditions at 20 ± 1 C. Aeration was performed to mix the cells in the medium. Different salt concentrations and culture times were applied to induce oil accumulation