Optimization of culture conditions for enhanced Dunaliella salina productions in mixotrophic culture.

Dunaliella salina (D. salina) is a green microalga known for its tendency to produce lipid and β-carotene. Fatty acid profile, lipid and β-carotene productions of the microalga D. salina cultivated under different mixotrophic conditions were assayed. Notably, in spite of a broad spectrum of substrates served, mixotrophic cultivations slightly affected the fatty acid composition, and as a result C16:0 and C18:0, C18:1, C18:2 and C18:3 were identified as main fatty acids. Lipid in dry weight biomass (DWB) hit a high of 24.3% at 5% of NaCL and linolenic acid in lipid reached a peak of 9.15% at 15% of NaCL in medium containing glucose and equal amounts of yeast extract and soy bean powder. One-factor-at-a-time was applied to elucidate the substrates which had noticeable impacts on β-carotene production. Glucose, meat peptone, titanium dioxide nanoparticles (TiO2 NPs), pH 7.5 and 5% NaCL were identified as key process parameters impacting β-carotene production. Following, the concentration of glucose, meat peptone and TiO2 NPs were optimized by using response surface method. The highest content of β-carotene, 25.23 mg/g DWB, was obtained in medium composed of (g/L); 22.92 glucose, 5 meat peptone and 0.002 TiO2 NPs.