Extração e caracterização de extratos lipídicos obtidos da biomassa de Tetradesmus (Scenedesmus) obliquus com propriedades antimicrobianas

Abstract

Microalgae have become a source promising renewable energy, in addition it provides bioactive substances such as carbohydrates, proteins, vitamins and lipids. Lipids perform several biological functions and are fundamental to the survival of most living beings. Extraction is an important step in the process of obtaining lipids from microalgal biomass and can be performed in different ways in order to achieve greater yield and cost-benefit. This study performed the extraction and characterization of the lipid extract from the biomass of Tetradesmus obliquus and evaluated its antimicrobial property. Microalgae was cultivated in Erlenmeyers flasks for 15 days until it reached the stationary phase of cell growth. The dry biomass remained in contact with the solvents hexane, ethyl acetate and ethanol P.A, all with different polarities, for 48 hours in which the lipid yield and the fatty acid profile were determined by gas chromatography. Extracts of hexane (EHT), ethyl acetate (EAT) and ethanol (EET) were subjected to antimicrobial activity at concentrations of 100, 50, 25, 12.5, 6.25 and 3.12 mg/mL against bacteria Staphylococcus aureus, Klebsiella pneumoniae e Escherichia coli. EET obtained the highest lipid yield with 1.49±0.01% in the first extraction, while EAT obtained 1.22±0.02% and EHT yielded 0.52±0.03%. In a second extraction EHT doubled the yield with 1.17±0.00% and EAT managed to reach 2.47±0.00%, presenting better results with an reextraction. The essential fatty acids most present in the extracts were α-linolenic (15.4% to 19.9%) and oleic acid (5.74% to 8.93%), which are most present in the extract EHT and EAT. EAT managed to achieve better results by inhibiting the growth of all bacteria to the lowest concentration. EHT was positive until the concentration of 6.25 mg/mL and EET only managed to totally inhibit the growth of the E.coli bacteria at the concentration of 100 mg/mL. So far, it can be concluded that the ethyl acetate solvent is more suitable for extraction of T. obliquus lipids with antimicrobial activity.