Effect of Salinity in fermentation medium on Chlorella vulgaris protein and lipid contents

Salinity-inducing effect on growth, metabolism of protein and lipid of Chlorella vulgaris were studied. In laboratory conditions, culture time of 144h lasted, the algal growth was the best under 0.0% NaCl, in which its biomass , chlorophyll , specific growth rate and productivity were 0.750g·L-1 , 39.50mg·g-1 , 0.225d-1 and 0.125g·L-1 ·d-1 , respectively, decreased significantly in higher 3.5% NaCl salinity. Additionally, the consumptions of nitrogen (N) and phosphorus (P) were 96.4% and 93.5%, with productivities of 9.10 and 0.71mg·L-1 ·d-1 , respectively. The algal protein was significantly higher in non-salinity with a final content of around 55.0% (W) from the dry biomass and a productivity of 68.40mg·L-1 ·d-1 . At the 96h, proline were higher in mezzo-salinities (2.5%) with the final contents of around 2.25% (W) , and the ratios of the highest (2.5% salinity) to the lowest value (0.0% salinity) was around 20.0. Similarly, at the 144h, lipid was higher in mezzo-salinities (2.5%) with the final contents of around 15.5% (W) and a productivity of 16.10mg·L-1 ·d-1 , which the ratios of the highest (2.5% salinity) to the lowest value (0.0% salinity) was around 3.6. Under hypo-and hyper-salinity treatments, both proline and lipid were lower. These results collectively suggested that NaCl salinity couldn’t only affect some nutrient consumption of nitrogen and phosphorus significantly, but also the algal biomass and components of protein, amino acid and lipid. Therefore, salinity could be modified to regulate physiological compositions of the algal cell during the cultivation of Chlorella vulgaris.