Carbon dioxide fixation and lipid storage by Scenedesmus obtusiusculus

An indigenous microalga was isolated from the springs in Cuatro Ciénegas, México. It was morphologically identified as Scenedesmus obtusiusculus and cultivated in bubble-column photobioreactors in batch operation mode. This microalga grows at 10% of carbon dioxide (CO2) showing a maximum CO2 fixation rate of 970 g m−3 d−1. The microalga, without any nutrient limitation, contained 20% of nonpolar lipids with a biomass productivity of 500 g m−3 d−1 and a maximum biomass concentration of around 6,000 g m−3 at 5% CO2 and irradiance of 134 μmol m−2 s−1. Furthermore, it was observed that the microalga stored 55.7% of nonpolar lipids when 5% CO2 was fed at 0.8 vvm and 54.7 μmol m−2 s−1 under nitrogen starvation. The lipid profile included C16:0, C18:0, C18:1n9t, C18:1n9c, C18:3n6 with a productivity of 200 g lipid m−3 d−1. Therefore, the microalga may have biotechnological potential producing lipids for biodiesel.