Improvement on lipid production by Scenedesmus obliquus triggered by low dose exposure to nanoparticles

Carbon nanotubes (CNTs), α-Fe 2 O 3 nanoparticles (nano Fe 2 O 3 ) and MgO nanoparticles (nano MgO) were evaluated for the effects on algae growth and lipid production. Nano Fe 2 O 3 promoted cell growth in the range of 0–20 mg·L −1 . CNTs, nano Fe 2 O 3 and nano MgO inhibited cell growth of Scenedesmus obliquus at 10, 40 and 0.8 mg·L −1 respectively. Neutral lipid and total lipid content increased with the increasing concentration of all tested nanoparticles. The maximum lipid productivity of cultures exposed to CNTs, nano Fe 2 O 3 and nano MgO was observed at 5 mg·L −1 , 5 mg·L −1 and 40 mg·L −1 , with the improvement by 8.9%, 39.6% and 18.5%. High dose exposure to nanoparticles limited increase in lipid productivity, possibly due to the repression on cell growth caused by nanoparticles-catalyzed reactive oxygen species (ROS) generation, finally leading to reduction in biomass and lipid production. Reduced accumulation of fatty acids of C18:3n3, C18:3n6 and C20:2 was observed in cells exposed to nanoparticles.