Extração e caracterização de lipídios microbianos do fungo filamentoso Aspergillus oryzae

Abstract

Microbial oils are a promising alternative to meet the nutritional demand of lipids essentially ingested through the diet. And the filamentous fungi belonging to this group stand out for their ability to synthesize high amounts of fatty acids when compared to other oleaginous microorganisms. Thus, the objective of this work was to evaluate the potential of the filamentous fungus A. oryzae for the accumulation of lipid and to promote lipid extraction using solvents in an ultrasonic bath, to characterize the oils obtained and compare the extraction yield for the different solvents and solvent mixture. The extraction of microbial lipid in an ultrasonic bath under the conditions: 80 min, 50ºC and solid: liquid ratio 0.5 g:50 mL showed more interesting results with the use of dry biomass corresponding to an efficiency of 84.0%, while for wet biomass presented efficiency of 50.1%. Lipid extraction with the solvents: ethyl acetate, heptane, hexane, methanol, ethanol and isopropanol showed extraction efficiency of respectively 96%, 94.3%, 94.6%, 100%, 84.0% and 93.7 %. The unsaturated fatty acid composition of the lipids extracted by the different solvents was predominant in relation to the saturated content for the polar solvents, whose percentage of the main fatty acids extracted was: 39 – 40% oleic acid (C18:1), 23 – 24% palmitic acid (C16:0) and 13 – 14% linoleic acid (C18:2) for the polar solvents. And for the nonpolar solvents the percentage of the main extracted fatty acids was: 41 – 42% oleic acid (C18:1), 36 – 33% palmitic acid (C16:0) and 12% stearic acid (C18:0). And for mixture of solvents: ethyl acetate: methanol, ethyl acetate: ethanol, ethyl acetate: isopropanol in the proportions 2:1, 1:1 and 1:2, a higher percentage of unsaturated fatty acids and the composition of the main extracted fatty acids was: 38 – 41% oleic acid (C18:1), 23 – 25% palmitic acid (C16:0) and 12 – 15% linoleic acid (C18:2). And in improving the process, it was possible to reduce the lipid extraction time in an ultrasonic bath to 40min, the initial temperature of the ultrasonic bath to 30ºC, which presented a lipid extraction efficiency of 90.7%. Therefore, the present work enabled the deepening of knowledge in the extraction of microbial lipids, thus contributing to the increase of scientific knowledge in the area.