Mass Cultivation of Nannochloropsis in Closed Systems

Nannochloropsis is a marine microalga commonly cultìvated in fish hatcheries as feed for rotìfers and to create a green water effect in larvae tanks (Fulks & Main, 1991; Lubzens et al., 1995). Because of its high content of eicosapentaenoic acid (EPA), Nannochloropsis has also been proposed as a source of this important dietary polyunsaturated fatty acid (Chini Zittelli eta/., 1999; Sukenik, 1999). Mass cultivation of Nannochloropsis is at present carried out in different kinds of large outdoor ponds and tanks (Okauchi, 1991; Sukenik, 1999), and in 50-500 l polyethylene bags or glass fibre cylinders usually kept indoors with artificial light (Fulks & Main, 1991). Severa! problems have been evidenced by the use of these systems, the most severe of which are low celi concentrations and productivity, and susceptibility to contamination (Borowitzka, 1997). Recently, research efforts have been directed toward the development of efficient closed photobioreactors, which have been successfully used for Nannochloropsis cultivation (Chini Zittelli eta/., 1999, 2000; Richmond & Zhang, 2001). This review presents the major results obtained in the cultivation of Nannochloropsis in closed systems, under either natura! or artificial illumination or a combination of both (see Chapter 20 for Nannochloropsis in open raceways).