Extraction of lipids from microalgae by ultrasound application: prospection of the optimal extraction method.

Microalgae have the ability to grow rapidly, synthesize and accumulate large amounts (approximately 20-50% of dry weight) of lipids. A successful and economically viable algae based oil industry will depend on the selection of appropriate microalgal strains and the selection of the most suitable lipid extraction method. In this paper, five extraction methods were evaluated regarding the extraction of lipids from Chlorella vulgaris: Bligh and Dyer, Chen, Folch, Hara and Radin, and Soxhlet. Furthermore, the addition of silica powder was studied to evaluate the introduction of more shear stress to the system as to increase the disruption of cell walls. Among the studied methods, the Bligh and Dyer method assisted by ultrasound resulted in the highest extraction of oil from C. vulgaris (52.5% w/w). Addition of powder silica did not improve the extraction of oil.

Bioprospecting for oil producing microalgal strains: evaluation of oil and biomass production for ten microalgal strains.

Microalgae have the ability to grow rapidly, synthesize and accumulate large amounts (approximately 20-50% of dry weight) of lipids. A successful and economically viable algae based oil industry depends on the selection of appropriate algal strains. In this study ten species of microalgae were prospected to determine their suitability for oil production: Chaetoceros gracilis, Chaetoceros mulleri, Chlorella vulgaris, Dunaliella sp., Isochrysis sp., Nannochloropsis oculata, Tetraselmis sp., Tetraselmis chui, Tetraselmis tetrathele and Thalassiosira weissflogii. The study was carried out in 3 L glass flasks subjected to constant aeration and controlled artificial illumination and temperature at two different salinities. After harvesting, the extraction of oil was carried out using the Bligh and Dyer method assisted by ultrasound. Results showed that C. gracilis presented the highest oil content and that C. vulgaris presented the highest oil production.

Vascular effects of a sulfated polysaccharide from the red marine alga Solieria filiformis.

Anticoagulant and antithrombotic properties of sulfated-polysaccharides (SP) from marine algae are extensively exploited. However, reports on the vascular effects of SP from red algae are rare in the literature. The polysaccharide from Solieria filiformis (Sf-SP) was isolated by ion exchange chromatography, analyzed by agarose gel electrophoresis and tested in male Wistar rats. The inflammation studies were performed using the paw-edema model and the relaxant activity in isolated aorta pre-contracted with phenylephrine. The anticoagulant effect was evaluated by the test of partial thromboplastin activation time. The SP (1 mg/kg) was not anti-inflammatory, but induced acute edema with maximal activity at 30 min (0.35 +/- 0.04 mL) compared to controls (0.05 +/- 0.03 mL). Cumulative addition of Sf-SP in phenylephrine-contracted tissues produced relaxation with maximal inhibition of 69% (IC50 29.3 +/- 9.0 microg/mL) at 300 microg/mL in comparison to controls (0.51 +/- 0.09 g). Sf-SP also extended human plasma coagulation time by 2.1 times. These substances could be used as important tools for the study of vascular alterations.