Enhanced production of biomass and lipids by supplying CO 2 in marine microalga Dunaliella sp.

Non-food-based biofuel feedstocks are in high demand worldwide. Among the various feedstocks, microalgae are the most promising feedstock for mitigating atmospheric CO 2 and producing biodiesel. In this study, various concentrations of CO 2 , from 0.03 to 12%, were used to investigate their effect on the cell growth, biomass and lipid production and fatty acid composition of Dunaliella sp. in a closed photobioreactor. The results showed that the highest biomass and total lipids, 521 mg/L/d and 40 mg/L/d, respectively, were produced with 5% CO 2 aeration during the logarithmic growth phase. The oleic acid (18:1n9c) and elaidic acid (18:1n9t) contents were increased approximately two fold. The physiological responses of Dunaliella sp. at 10% CO 2 were similar to those at 5% CO 2 . Therefore, the present results suggest that 5–10% is a suitable CO 2 concentration range for Dunaliella sp. growth to mitigate atmospheric CO 2 and increase biofuel production.