Effect of High Co2 Concentrations on a Microalgae Lipidome

Lipids are of interest as potential byproducts of CO 2 mitigation systems. We characterize the effect of different CO 2 atmospheres (air, 25 and 50% v/v CO 2 ) on Desmodesmus abundans RSM lipidome, enriched for eight years to these conditions. Although batch cultures grew similarly, more biomass was generated at high CO 2 (1.2- to 1.9-fold increase). Lipidome analysis at late exponential and early and late stationary phase revealed 100 putative lipidic features with significant changes grouped into five distinct clusters. Clusters 1 and 2 are characterized by glycerolipids (GL, 66 to 100%) and clusters 3 to 5 as glycerophospholipids (GP, 76 to 100%). Under air, most features of clusters 1, 2, and 5 were nearly constant through time, but under high CO 2, lipid profiles seemed to be determined by dCO2 availability. At dCO2 depletion, GL probably acts as a precursor of GP. At stationary phase, distinct cell maintenance strategies seemed to occur between cultures as lipids or starch were consumed at 25 and 50% CO2 to generate GP or GL. Also, high CO2 triggered an increase in pigments but did not affect lipid or starch content, except for a 1.6-fold increase in lipids under 25% CO2 later consumed. Results suggest different responses to CO2 among cultures; however, at this moment, it is not possible to elucidate whether differences are caused by CO2 treatment or long-term acclimation, or both. Studies should evaluate selected cultures under particular growth conditions to generate specific lipid byproducts for application.