Using high CO₂ concentrations to culture microalgae for lipid and fatty acid production: Synthesis based on a meta-analysis

To gain a comprehensive understanding of cultivating microalgae for lipid and fatty acid production with high CO₂, this study conducted a meta-analysis based on 757 data sets from 51 papers for the first time. The findings show that high CO₂ concentrations (0.1–30%) generally promote microalgal growth, whereas extreme high CO₂ levels (30–50%) usually exhibit negative effects. High CO₂ levels (0.1–30%) also commonly stimulate cellular lipid accumulation. Therefore, high CO₂ levels (0.1–50%) increase lipid productivity of both freshwater and marine microalgae, particular for Chlorophytina. These elevated CO₂ levels (0.1–30%) reduce saturated fatty acid content of microalgae but enhance the content of unsaturated and polyunsaturated fatty acids, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Advanced molecular editing techniques, e.g., CRISPR-Cas9, can be utilized to improve microalgal tolerance to flue gases that contain hazardous compounds while condition optimalization for maximal use of CO₂ in the production of microalgae with high lipid content should also be conducted in future. This research provides crucial insights for designing and optimizing microalgae cultivation with high CO₂ to produce lipid and fatty acids.