GROWTH AND EICOSAPENTAENOIC ACID PRODUCTION BY PHAEODACTYLUM-TRICORNUTUM IN BATCH AND CONTINUOUS CULTURE SYSTEMS

Maximum specific growth rate (mu(max)) of Phaeodactylum tricornutum increased with increasing culture reactor surface-to-volume ratio. Values for mu(max) of 0.647, 0.377 and 0.339 day-1 were observed for the 75-mL tube, 5.6-L tank and the 16-L tank, rerpectively. Higher biomass was achieved in the 75-mL batch culture tube under continuous light as compared with light cycle conditions. Palmitic acid, palmitoleic acid and eicosapentaenoic acid (EPA) accounted for over 60% of total fatty acids in the batch tube culture, with EPA content increasing to a maximum after three days. In chemostat cultures, run at dilution rates of 0.15 day-1 (0.45 of mu(max)) and 0.3 day-1 (0.9 of mu(max)), cell concentration reached a steady state of 2.18 and 0.7 g/L, respectively, while contents of EPA per liter of culture at steady state were 100.9 and 82.5 mg/L, respectively. At both dilution rates, EPA content of total fatty acids was the same (35.0-35.2%). At a dilution rate of 0.3 day-1, the continuous culture system manifested productivities of 0.51 g/L/d and 25.1 mg/L/d for biomass and EPA, respectively.