Metabolic switching: synergistic induction of carotenogenesis in the aerial microalga, Vischeriahelvetica, under environmental stress conditions by inhibitors of fatty acid biosynthesis

Objectives To investigate the roles of fatty acid biosynthesis in carotenogenesis in the high-lipid accumulating aerial microalga Vischeria helvetica KGU-Y001, we cultured algal cells with fatty acid biosynthesis inhibitors. Results Under nitrogen-deficient, high-light (200 µmol photons m −2 s −1 ) conditions, the alga accumulated 6.2 mg carotenoids g −1 dry weight cells (DWC) after 1 week of culture. The total fatty acid content increased gradually, and reached 290 mg g −1 DWC after 9 weeks. When algal cells were cultured with a fatty acid biosynthesis inhibitor (molinate) under nitrogen-deficient, high-light conditions for 1 week, carotenoid accumulation was synergistically increased to 2.4 times that in algal cells cultured without the inhibitor in nitrogen-deficient, low-light conditions (40 µmol photons m −2 s −1 ). The synergistic induction of carotenogenesis was suppressed by an inhibitor of c-jun N -terminal kinase, a mitogen-activated protein kinase-like protein. Conclusion In a commercial context, carotenoid production could be increased by using fatty acid biosynthesis inhibitors to redirect metabolic flux to carotenoid biosynthesis instead of fatty acid synthesis.