BIOMASS NUTRIENT PROFILES OF THE MICROALGA PHAEODACTYLUM TRICORNUTUM

The microalga Phaeodactylum tricornutum was cultured under various conditions in an external tubular photobioreactor and in a bubble column. The proximate composition (moisture, ash, crude protein, available carbohydrates, fiber, lipids and energy), nitrate, nucleic acids, mineral elements (Na, K, Ca, Mg, Fe, Cu, Zn, Mn, P, S, As, Pb, Cd), C/N ratio, fatty acids and pigments (total carotenoids, carotenoid class and chlorophylls) were analyzed. On average, the biomass contained 36.4% crude protein, 26.1% available carbohydrates, 18.0% lipids, 15.9% ash and 0.25% neutral detergent fiber, on a dry wt basis. The mineral element contents in 100 g dry biomass were: Ca (1910 mg), K (1720 mg), Na (1430 mg), S (1050 mg), Mg (555 mg), Zn (373 mg), (Mn 31.4 mg), Cu (8.4 mg), and P (269 mg). Toxic heavy metal contents were negligible. The fatty acid content was (on percent dry wt): 0.65% in 14:0;1.28% in 16:0; 1.48% in 16:lω7; 0.34% in 16:2ω4; 0.75% in 16:3ω4 and 2.50% in 20:5ω3. Nutrient composition of biomass was highly influenced by means of the residence time in the culture bioreactor and the external irradiance. The biomass produced at low external irradiance was richer in protein and eicosapentaenoic acid.