Effect of high CO2 concentrations on Desmodesmus abundans RSM lipidome

Lipids are of interest as potential byproducts of CO2 mitigation systems. We characterize the effect of different CO2 concentrations in air (0.04 % pure air, 25 % and 50 % v/v CO2/air) on Desmodesmus abundans RSM lipidome, adapted for eight years to these conditions. Batch cultures grew similarly but more biomass was generated at high CO2 (1.2- to 1.9-fold increase). Lipidome analysis at late exponential, and early and late stationary phase revealed 100 putative lipid features with significant changes grouped into five distinct clusters. Clusters 1 and 2 characterized by glycerolipids (GL, 66–100 %) and clusters from 3 to 5 as glycerophospholipids (GP, 76–100 %). Under air (0.04 % CO2), most features of clusters 1, 2, and 5 were nearly constant through time, but under high CO2, lipid profiles seemed to be determined by dCO2 availability. At dCO2 depletion, GL probably acts as a precursor of GP. During 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, respectively. Also, under high CO2, both cultures exhibited an increase in pigments but only under 25 % CO2 a 1.6-fold increase in lipids was observed, which were 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.