Subculture of the isolated species was done
with autoclaved seawater which was filtered through 0.45 mm Millipore and enriched with F/2 medium at the room temperature of 25°C and the water temperature of 20°C with salinity 30 ppt. Most species grow best at a salinity that is slightly lower than that of their native habitat, which is obtained by diluting sea water with tap water. Light (4500 ± 400 Lux) was provided and maintained 12:12 h light:dark cycle. The isolation process was carried out until getting the mono strain of the S. costatum, for getting the bacteria free strain, various doses of antibiotics were used and absolutely bacteria free mono strain was found above a dose of 200 units-penicillin/ mL, 200 µg-Streptomycin/mL solution were found to be lethal for S. costatum and cells were grown in axenic condition. The mono species of S. costatum was inoculated for a mass culture. The experiments were conducted in 5 liter conical flasks with 50 ml and 20 liters of glass tank with 200 ml of 4 5 days old exponentially grown algal cultures (Fig. 1). The cell density was estimated at every 24 hours intervals in all the experiments.