Comparative analysis of microalgae metabolism on BBM and municipal wastewater during salt induced lipid accumulation

Abstract This study showed that among stress factors, salinity has the greatest effect on accumulation of neutral lipids in microalgae strains that normally produce carbohydrates. Parachlorella kessleri IC-11 cultivation of autoclaved municipal wastewater with 30 g L−1 salt added revealed neutral lipids accumulation and increase in the total lipids content (up to 31.0 ± 1.8%). In saline wastewater P. kessleri IC-11 reduced COD by 11.46 ± 0.43%, while NH4+ was completely assimilated. PCA and PLS-DA analysis of its metabolism on BBM and wastewater revealed that the greatest contribution to the change in metabolism under salt stress was accomplished by a decrease in the following metabolites: adenylate (purine metabolism) on BBM medium and proline (arginine and proline metabolism) along with citric acid (citric acid cycle) on wastewater in stationary phase. Differences in metabolism during cultivation in both media should be taken into account when identifying potential target genes for metabolic engineering of lipid production in microalgae.