Revealing Tag synthesis pathway in the green microalga Haematococcus pluvialis a source of triacylglycerides for biodiesel and valuable co-products.

PAOLA SCODELARO BILBAO; GABRIELA SALVADOR; PATRICIA LEONARDI

Congreso; Reunión Conjunta de Sociedades de BioCiencias; 2017

SAIB

Haematococcus pluvialis is an oleaginous microalga known as important source of the red carotenoidastaxanthin. Recently, we proposed H. pluvialisas a potential source of triacylglycerides (TAG) for biodiesel production, andof phytosterols with potential nutraceutical properties. In this work, our purposewas to study the metabolic pathways involved in TAG synthesis induced byhigh-light stress in H. pluvialisUTEX 2505. For this end, the strain was grown in Bold´s Basal Medium underhigh-light intensity or control light for 1, 2 and 3 days. Then, the lipidcontent and the expression of the enzymes kwon to be involved in lipidmetabolism in plants were analyzed. High-light stress significantly stimulated TAGand phytosterol synthesis and accumulation (P<0.01) in all the conditionstested. Red Nile staining analyzed by confocal microscopy confirmed thepresence of cytoplasmic droplets after H.pluvialis high-light exposure. The use of propranolol, a lipin inhibitor,significantly diminished (P<0.01) TAG synthesis induced by high-lightintensity. Western Blot analysis revealed that high-light stress significantlyinduced the expression of the fatty acid synthase (FAS) complex (P<0.01)lysophosphatidic acid acyltransferase (LPAAT) (P<0.01) and diacylglycerolacyltransferase (DGAT) enzymes (P<0.01). In addition, qPCR also showed increasedmRNA levels of the above-mentioned enzymes. On the other hand, high-light alsoinduced the expression of the monoacylglyceride (P<0.01) and diacylglyderide(P<0.01) lipases. However, no significant changes (P<0.05) were observedin the released of glycerol to the medium after high-light stress. Together,these results suggest that TAG synthesis in H.pluvialis occurs de novo throughof stimulation of the fatty acid synthesis pathway and induction of the Kennedy pathway under light stress.Our results constitute the starting point to design molecular strategies forincreasing the synthesis of valuable products from H. pluvialis.