Exploring salinity-induced biochemical changes in Chlorella vulgaris using statistical modelling

The impact of high salinity stress on the growth and nutrient uptake of Chlorella vulgaris was investigated using a two-stage cultivation approach. Changes in the biochemical composition of the biomass were statistically evaluated through principal component analysis (PCA) and multiple linear regression (MLR). The presence of 150 mM NaCl promoted higher biomass accumulation (978 ± 11 mg L^-1) and did not affect the nutrient removal rates. Elevated concentrations (> 300 mM) induced negative effects, resulting in microalgae mortality. The highest lipid (24% ± 1% DCW) and carbohydrate (32.3% ± 0.6% DCW) contents were achieved with 300 mM NaCl on days 7 and 4, respectively. Moreover, 150 mM NaCl led to the highest lipid productivity (23.4 mg L^-1 d^-1) only in 2 days of stress. PCA and MLR confirmed that the lipid content was positively associated with salinity and time of exposure and that the pigments were strongly affected by the exposure time.