Regulation of Light Spectra on Cell Division of the Unicellular Green Alga Haematococcus pluvialis: Insights from Physiological and Lipidomic Analysis

Abstract

Commercial scale production of natural astaxanthin is currently conducted through cultivation of the green alga Haematococcus pluvialis. This study comprehensively investigated the impact of seven different light spectra on the growth, morphology and photosynthesis of H. pluvialis vegetative cells. Further, the lipidomes of vegetative H. pluvialis grown under various light spectra were qualitatively and quantitatively analyzed using liquid chromatography/mass spectrometry (LC/MS). The results showed the existence of blue light—alone or with red light—promoted cell division, while pure red light or white light enabled increased cell sizes, cellular pigment, starch and lipid contents, and biomass production. Although the photosynthetic performance of H. pluvialis measured as chlorophyll a fluorescence was not significantly affected by light spectra, the lipid profiles, particularly chloroplast membrane lipids, showed remarkable changes with light spectra. The contents of most lipid species in the blue/red light 1/2 group, which showed the fastest cell division, remained at a moderate level compared with those under other light spectra, indicating the fastest dividing cells were featured by a fine-tuned lipid profile. From biotechnical perspective, this comprehensive study can provide insights into the development of appropriate light regimes to promote the cell density or biomass of H. pluvialis mass culture.