Biochemical quality of marine unicellular algae with special emphasis on lipid composition. II. Nannochloropsis sp.

The eustigmatophyte, Nannochloropsis sp., contains relatively large amounts of valuable lipids and is commonly grown as food source for commercial application in aquaculture. In this study we evaluated the effect of environmental conditions such as light intensity, nitrogen availability and temperature on cellular chemical composition with special emphasis on fatty acid distribution in cultures of Nannochloropsis sp. continuously grown under laboratory-controlled conditions. Seasonal variations in cellular chemistry were further assessed using large-scale outdoor shallow ponds, aimed at mass production of Nannochloropsis for application in an aquaculture hatchery. The percentage of the polyunsaturated long-chain fatty acid, eicosapentaenoic acid, in the algal biomass varied between 1.6 and 3.8% (w/w). In spite of significant variations in cellular protein content, the amino acid composition of Nannochloropsis biomass remained fairly constant during the different production seasons. Variations in the fatty acid composition of the algal biomass are attributed to differences in seasonal climatic conditions and diurnal cycles in light intensity and temperature. This study demonstrates the feasibility of culturing algal biomass of a high chemical quality for various applications in aquaculture hatcheries.