Optimum medium for largescale culture of Tetraselmis tetrathele

The prasinophyte Tetraselmis tetrathele is an alga commonly used as live food for aquatic animal larvae. The alga is usually cultured in Guillard and Ryther medium (Guilliard F)or a fertilizer enriched seawater medium for the large-scale culture of Nannochloropsis. However, Guillard F is too complicated to use for large-scale culture, and some fertilizers are impure and insoluble. A new enriched seawater medium for the large-scale culture of T. tetrathele (ES-T.T.)was formulated by modifying the Guillard F medium. NaNO 3 , NaH 2 PO 4 , Fe-EDTA and MnCl 2 were selected as essential additives for the medium by systematically removing each additive of Guillard F. Results from axenic culture experiments, using an artificial seawater medium, the required amount of these additives was estimated to be, 150 mg NaNO 3 , 10 mg NaH 2 PO 4 . 2H 2 O, 15 mg Fe-EDTA and 360 µg MnCl 2 . 4H 2 O, per liter of seawater. The productive rate of T. tetrathele in ES-T.T. was higher than in a fertilized medium in a 100 liter outdoor culture experiment. In 10 liter indoor culture experiments, no significant difference was detected in production rates between ES-T.T. and Guillard F. Therefore, ES-T.T, is simple and effective to use as a large-scale culture medium for T. tetrathele.