Develop the Suitable Culture Media for Marine Microalgae Tetraselmis Species

Abstract

In the present study, the growth performance of Tetraselmis sp. was observed in different nutrient media (TMRL, Guillard, Conway, maxicrop, fertilizer and seawater) and in salt concentrations (15ppt, 20ppt, 25ppt and 30 ppt). This study also evaluated the growth performance of rotifer (Brachionus plicatilis) developed by microalgae cultured in various nutrient media. The microalgae, Tetraselmis sp. was collected from BFRI (Bangladesh Fisheries Research Institute), Marine Water Station, Cox’s Bazar, Chittagong and the rotifer (Brachionus plicatilis) was collected from Bangladesh Fisheries Research Institute (BFRI), Brackish Water Station, Paikgacha, Khulna. The experiment was conducted in 500ml plastic bottles, with working volume of 200ml, temperature 25 ± 1°C, with constant light (1600-2000 lx) and aeration. Each experiment was conducted with the replication of three. The results evidenced that maximum cells number in stationary phase were noticed in Conway medium (241±5.178×10⁴ cells/ml) followed by TMRL medium (225.148 ±4.62×10⁴ cells/ml), Guillard f/2 medium (202.333±4.91×10⁴ cells/ml), seawater (102.889±7.27×10⁴ cells/ml), Maxicrop medium (99±3.46×10⁴ cells/ml) and commercial fertilizer (53.67±6.69×10⁴ cells/ml). However, the production cost for the preparation of 100 ml TMRL medium was the lowest among the three best medium, while Tetraselmis sp. growth was higher. The production cost of Guillard (298.451Tk/100ml) was 17.47 and 2.01 times higher than TMRL (17.08 Tk/100ml) and Conway (148.32 Tk/100ml) respectively. In the second experiment, the cell density of Tetraselmis sp. in 30ppt salinity was significantly (p<0.05) higher as 232.889±5.755×10⁴ cells/ml, followed by 25ppt (207±6.11×10⁴ cells/ml), 20ppt (92±2.309×10⁴ cells/ml) and 15ppt salinity (84±4.73×10⁴ cells/ml). In the third experiment, the rotifer fed on Tetraselmis sp. cultured in Conway medium showed the highest (p<0.05) population growth (56.11±1.25ind./ml), compared to that fed on Tetraselmis sp. developed with TMRL medium (20.333±0.882ind./ml) and Guillard f/2 medium (18±1.15ind./ml). The results of the present study indicate that the TMRL medium could be a suitable and cheap culture medium for the enhancement of Tetraselmis sp. biomass in 30ppt salinity. The result also recommend that Tetraselmis sp. developed with Conway medium could be a suitable food for the stock culture of locally isolated rotifer B. plicatilis.