Improving modified natural sea water medium for the growth of Dunaliella bardawill DCCBC15

Abstract

Beta-carotene, the major carotenoid accumulated in Dunaliella, is a valuable compound, in high demand as a natural food coloring agent, pro-vitamin A, additive to cosmetics, and health food. Dunaliella bardawil is a marine alga currently capturing general public attention due to its high potential for beta- carotene production. This special coumpound can be accumulated up to more than 10% of the total dry weight under carotenogenic conditions, i.e, high irradiance, high temperature, high salt concentration and nutrient deficiency. However, beta-carotene content in Dunaliella cells depends much upon growth conditions and nutrient components. A low cost natural seawater medium yielding better growth (MD4) has been investigated (Tran et al., accepted manuscript); however, the cell growth declined after 12 days of culture due to nutrients limit. Hence, the aim of this study was to further improve the effectiveness of this modified natural seawater medium. Algal cultures were subjected to 13 treatments (TM1  TM13) using various chemicals and their combination (NPK, KNO , KH PO ) with different concentrations. Cell density (cell 3 2 4 count, optical density), chlorophyll and total carotene content were analyzed and compared from these treatments. The result obtained revealed that TM4 (NPK 0.15 g/l) was the best feeding treatment. Other treatments (TM5, TM6, TM7 and TM11, TM12, TM13) could also be potential at least for sustaining the culture. Keywords: Algae, carotene, chlorophyll, cultivation, Dunaliella, medium.