Screening High CO₂-Tolerant Oleaginous Microalgae from Genera Desmodesmus and Scenedesmus

Microalgae from genus Scenedesmus sensu lato (including Desmodesmus and Scenedesmus) were reported to be particularly suitable candidates for CO₂ biomitigation. In this study, 16 strains from Scenedesmus sensu lato were obtained from different climate zones of China and their phylogenetic positions were determined. Seven strains out of the 16 showed high CO₂ tolerance and grew much faster under 20% CO₂ than air condition. Two representatives from genera Desmodesmus (NMD46) and Scenedesmus (HBX310) respectively were selected due to their higher lipid productivity, and the maximum value of 146 mg L^-1 day^-1 was achieved in NMD46. Triacylglycerols increased with the rising of CO₂ levels from 0.04 to 15% in NMD46, while they changed little in HBX310. High CO₂ level decreased the polyunsaturated fatty acid content in NMD46 but increased it in HBX310. NMD46 is more suitable for standardized biodiesel production in view of its lipid and fatty acid composition responses to high CO₂.