Abstract
Nannochloropsis oculata (also called marine chlorella) is a marine unicellular algae used as a feedstuff in the Japanese aquaculture industry. Due to the high fat and icosapentaenoic acid (EPA) content, it serves as high nutritional feed in the food chain for fish hatchlings. EPA content of the organism could be modulated from 20 % to 40 % total extractable fat by varying the culture conditions. The maximum fat content of Nannochloropsis was about 30 % by weight, and the optimal cell density of 2.5×108 cells/mL achieved using a specially developed outdoor tank technology. Nannochloropsis lipid was predominantly polar (phospholipid and glycolipid), and the glycolipid fractions (mono-and digalactosyl diacylglycerols) contained over 70 % EPA in their fatty acid moieties. Due to the absence of docosahexaenoic acid (DHA), EPA from Nannochloropsis could be easily purified to over 95 %. Dietary supplementation of spontaneously hypertensive rats with intact Nannochloropsis cells resulted in a significant reduction of the saltinduced increase in blood pressure. However, these high fat/high EPA microalgae may be of the greatest use to the aquaculture industry as feed for zooplankton (brine shrimp and rotifers) cultures. Nannochloropsis-fed zooplankton was found to serve as a highly nutritious live feed which significantly increased the survival of the hatchlings of many cultured fish.
