ECOPHYSIOLOGICAL CONSIDERATIONS IN THE OPTIMIZATION OF EICOSAPENTAENOIC ACID PRODUCTION BY NANNOCHLOROPSIS-SP (EUSTIGMATOPHYCEAE)

Polyunsaturated fatty acids that belong to the omega-3 group are essential fatty acids for the development of marine organisms and important in a balanced human diet. Several classes of algae, including the class of Eustigmatophyceae, are the primary source of those important compounds. The marine eustigmatophyte Nannochloropsis sp. contains a relatively large quantity of the omega-3 poly-unsaturated fatty acid eicosapentaenoic acid (EPA). The cellular content of EPA can be regulated by growth conditions. Thus, to maximize EPA production by Nannochloropsis, an optimal set of environmental conditions should be determined. The effects of light intensity, nitrogen availability and temperature on cellular EPA content and other growth parameters were evaluated in laboratory cultures and can be applied to outdoor algal production systems. Maximal cellular content of EPA was obtained in nutrient sufficient cultures grown at low light conditions (35-mu-mol quanta m-2 s-1), and a temperature which was slightly lower than the optimal temperature for growth. However, that set of conditions caused a significant decrease in cellular growth rate, thus reducing EPA productivity. Consequently, the highest EPA productivity is expected in growth conditions that support maximal biomass production rate, and slightly differ from the conditions that would yield biomass with maximal EPA content.