Culture medium optimization for enhanced β-carotene and biomass production by Dunaliella salina in mixotrophic culture

•Dunaliella salina could be used as a potential feedstock for β-carotene and biomass production.•Nutrients of C, N, and P were optimized for D. salina in mixotrophic culture.•Highest β-carotene and biomass content of 8.12 mg g−1 and 1.21 g L−1 obtained, namely.•β-carotene and biomass content showed 195% and 175% increase respectively, in optimized culture.•Mixotrophic culture was proposed as a favorable culture method for β-carotene production.

Dunaliella salina is a well-known microalga with a high pharmaceutical and industrial value. It contains a high fatty acid, protein and β-carotene content that makes it a fascinating choice for human food or feed. To improve the β-carotene and biomass production and therefore its nutritional value in mixotrophic culture, a well-known commercial medium was optimized to the most favorable nutrient level using response surface methodology approach. The optimal growth medium conditions defined to be at a glucose concentration of 15.0 g L−1, a nitrate concentration of 1.80 g L−1, and a phosphate concentration of 0.013 g L−1. Suggested culture medium conditions allowed obtaining an 8.12 mg β-carotene per gram dry weight (DW) and biomass concentration of 1.015 g L−1. The β-carotene and biomass contents were increased 1.95 and 1.75 folds than their original values, respectively.