New insights into lipid metabolism of Haematococcus pluvialis in response to high-light stress.

PAOLA SCODELARO BILBAO; GABRIELA SALVADOR; PATRICIA LEONARDI

Paraná

Congreso; 54th Annual Meeting Argentine Society for Biochemistry and Molecular Biology; 2018

SAIB

Theoleaginous unicellular microalga Haematococcuspluvialis is being intensely studiedas a source of carotenoids and lipids with potential biotechnological andbiomedical applications. The aim of this study was to analyze the effect ofhigh-light stress on the regulation of triacylglyceride (TAG) and sterolsynthesis in H. pluvialis UTEX 2505.After 24 hours of high-light exposure, both lipid classes significantlyincreased compared to the control condition. As expected, the use of inhibitorscerulenin, propranolol, xanthohumol and A922500 significantly decreased TAGsynthesis under high-light stress, while mevastatin and 25-hydroxycholesterolreduced sterol content. These results together with qPCR and Western blotanalyses revealed some of the enzymes of H.pluvialis involved in lipid synthesis in response to high-light. Inaddition, we observed that TAG inhibitors also reduced sterol content whilesterol inhibitors diminished TAG production, denoting coordination between bothsynthesis pathways. Fosmidomycin, a specific inhibitor of the non-mevalonatepathway of isoprenoid biosynthesis, reduced total carotenoid content andantioxidant capacity together with TAG and sterol content. Finally, inhibitionof carotenoid, TAG and sterol synthesis significantly reduced cell viabilitysuggesting their participation in H.pluvialis survival and adaption to high irradiance. These findings revealfeatures of lipid synthesis and function of H.pluvialis under high-light stress, and points towards new possiblemolecular targets to enhance lipid production in microalgae