CO2 fixation and lipid production by microalgal species

Microalgal species Nannochloropsis limnetica, Botryococcus braunii, and Stichococcus bacillaris were compared for their ability to grow, remove CO2, and accumulate lipids in their biomass under CO2-enriched atmosphere. Overall, N. limnetica outperformed the other two cultures and distinctly exhibited higher specific growth rate (0.999 d−1) and CO2 fixation rate (0.129 gL−1 d−1) with a high specific lipid yield (40% w/w). The volumetric CO2 fixation rate for all three species was validated with biomass productivity and mass transfer methods (P<0.005 and R2=0. 98). At 10% CO2, N. limnetica showed one-and-a-half times more carbon fixation efficiency over B. braunii, and S. bacillaris. On the other hand, total fatty acids of N. limnetica dispalyed an apparent increase in oleic acid. Whereas, under similar conditions, N. limnetica exhibited reduced eicosapentaenoic acid. These findings suggest that at high CO2 conditions, N. limnetica proved to be an efficient CO2 capture algal system and can be considered for biofuel applications.