Metabolomic and network analysis of astaxanthin-producing Haematococcus pluvialis under various stress conditions

Various combinations of acetate (Ac), Fe2+ and high light (HL) stress conditions were evaluated to maximize astaxanthin accumulation and biomass production in Haematococcus pluvialis, and then GC–MS and LC–MS based metabolomics were applied to determine molecular mechanisms responsible for enhancing astaxanthin accumulation under the stress conditions. With the optimized analytical protocols, the GC–MS and LC–MS analyses allowed identification of 93 stable and 24 unstable intracellular metabolites from H. pluvialis, respectively. In addition, a metabolic network was constructed based on GC–MS metabolomic datasets using a weighted correlation network analysis (WGCNA) approach. The network analysis uncovered 2, 1 and 1 distinguished metabolic modules highly associated with HL, Fe2+ & HL, and Ac & Fe2+ & HL conditions, respectively. Finally, LC–MS analysis found that AKG, Glu and R5P may be metabolites associated with the Fe2+ & HL condition. The study provided the first metabolomic view of cell growth and astaxanthin accumulation in H. pluvialis.