Estudo ecofisiológico de Haematococcus pluvialis
Santos, Alexsandro Claudino dos
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The microalgae Haematococcus pluvialis has been studied as one of the main natural sources of astaxanthin carotenoid, potent antioxidant with applications in the nutraceutical and cosmetic industry. H. pluvialis is a microalgae Chlorophyceae whose life cycle includes a phase encystment with high pigment production. In recent years there has been increased activity, processes and applications involving the use of H. pluvialis and its biomass, however H. pluvialis culture do not achieve generally high biomass and species is considered delicate, a slow-growing. Thus, the production and use of the pigment depends on the microorganism and biological, physical and chemical interactions which result in high production of green cells which subsequently form red astaxanthin filled cysts. In this study we sought to optimize the vegetative growth of microalgae, increased the final biomass yield in crops. To this end we investigated the composition of the nutrient medium different pHs and culture methods (sealed vs continuous). Determination of photosynthetic efficiency and energy dissipation were used to infer the cellular health in green flagellates, evaluating the different experimental conditions on microalgae. Intracellular biochemical composition analyzes were performed by determining the concentration of proteins, lipids and carbohydrates in addition to the fatty acid composition. The study was initiated by investigating different nutrient media the growth and biomass production and the results showed that modified Oligo LC medium containing ammonium bicarbonate four times more concentrated nutrients and the remaining 2 times, resulting in improved production of biomass. A procedure then to study the influence of pH on vegetative growth, photosynthetic efficiency and biochemical composition of H. pluvialis. For this purpose we used pH buffers (MES, HEPES, and PIPES), and the results showed a higher germination cysts and higher growth rate in buffered at pH 6.3 cultures (growth rate 0.45 d-1; MES buffer). These findings that the production of H. pluvialis can proceed in the absence of a lag phase in cultures inoculated with cysts. Pigments and lipids related to cell wall dominated at pH 6.3 and palmitic acid (C16:0) and linoleic acid (C18:2n6c) were the most abundant fatty acids. PH in the 6.7 and 7.2 crops showed the highest content of polyunsaturated fatty acids, 6% higher than the control. Regarding the methods of cultivation, continuous were better. The biomass showed higher protein content and the larger culture growth rate and biomass of the sealed. The photosynthetic activity and its parameters suffered significant variations in continuous cultures. H. pluvialis responded better as the photosynthetic parameters in various light intensities when in continuous culture, despite the saturation irradiance was higher in batch cultures.