Bioprospecção de ácidos graxos em microalgas isoladas da região semiárida da Paraíba e ensaios com espécies potencialmente produtoras de biodiesel em condições de estresse.

Abstract

The search for viable energy alternatives, low cost, sustainable and can replace the use of fossil fuels has increased. In this context, biofuels derived from microalgae become a promising option either from the economic point of view as from the environmental point of view. The cultivation of microalgae produce higher amount of biomass in a short time and require large areas for their production as with sugarcane used for ethanol production, or soybean in the case biodiesel. This study aimed to characterize the potential for production of fatty acids from microalgae isolated from the semiarid region of the state of Paraiba kept growing in monospecific cultures of microalgae bank of LARBIM / UFPB and select potentially producing species of these compounds in order to grow them different stress conditions in order to increase the final yield of the fatty acids of interest for biodiesel production. The cultures were developed using the means Zarrouk and toilet in a growth chamber at 25 ° C ± 1 ° C equipped with lighting system, with a photoperiod of 12 hours. 12 strains included representatives of groups of cyanobacteria and green algae were studied in seven species. The quantification of each fatty microalgae studied acids was determined by gas chromatography. Two species Pediastrum tetras (D121WC) and Scenedesmus acuminatus (D115WC) showed levels of fatty acids 802.1% compared to 211.1% in soybeans compared to soybean, respectively. Therefore these species were grown under different conditions of stress under the same conditions of temperature and photoperiod, using photic, thermal and nutritional stresses. At the end of each experiment were determined for each condition tested, the levels of proteins, lipids and carbohydrates. The growth curves were avidly by measuring in vivo fluorescence in triplicate, and all growth parameters were analyzed for each species tested. Observed a higher rate of cell division per day in D112Z (0.71 divisions / day) species. The levels of fatty acids in strain D121WC increased more than twice on condition of photic stress. As for the species D115WC was an increase in the yield of fatty acid to condition it to heat stress of 590.8% compared to soybean. Although the two potentially important for the production of biodiesel tested species (Pediastrum tetras and Scenedesmus acuminatus) are, it is evident that their physiological responses to stress conditions are not the same.