The effect of salinity stress on the biofuel production potential of freshwater microalgae Chlorella vulgaris YH703

Microalgae are considered to be a promising alternative feedstock for biofuel production to prevent global warming and the depletion of fossil fuel. In this study, the effect of NaCl on biofuel production potential of freshwater microalgae Chlorella vulgaris YH703 was studied. During the first stage of cultivation, microalgae biomass has increased by 1.3 times in cultivation medium with 30 mM NaCl compared to the control. During the second stage of cultivation, salinity stress of 500 mM NaCl for 2 days has resulted in up to 24.5% lipid (12.7% in control). So the biofuel production potential has increased by 2.5 times during two-staged cultivation combined with NaCl treatment which means it is an efficient strategy to enhance biofuel production potential of Chlorella vulgaris YH703. In order to understand accumulation of lipid in freshwater microalgae Chlorella vulgaris YH703 under the salinity stress, it was also studied the changes in the level of several stress biomarkers such as hydrogen peroxide, APX (ascorbate peroxidase-antioxidative enzyme) and proline. Under the condition of NaCl stress, the amount of H2O2 and Proline and the level of APX activity in microalgae are greatly increased and this shows that Chlorella vulgaris YH703 is a specie that is tolerant to the oxidative stress which results in high salinity concentration. [Display omitted] •Chlorella vulgaris YH703 is tolerant to salinity stress, which is a promising feedstock for biofuel production.•Biomass productivity of microalgae was increased by 1.3 times in 30 mM NaCl treatment.•Lipid content in microalgae has increased to 24.5% (12.7% in control) under 500 mM NaCl stress for 2 days.•Two-staged cultivation combined with NaCl treatment is effective approach to increase the biofuel production by 2.45 times.