THE NUTRIENT-INDUCED RESPONSE OF CARBON ALLOCATION AND PRODUCTIVITY OF MICROALGAE Dunaliella Salina

Carbon allocation and productivity arc important for micro-algal applications. The effects of nitrogen and phosphorus supplies on carbon allocation and productivity of Dunaliella salina were investigated. The results indicated that sufficient NP supplies were necessary for D. salina growth, protein, and carbohydrate production. Carbohydrate proportion in cells remained constant whereas lipid and protein proportions changed upon different N concentrations or sources; while protein, carbohydrate, and lipid proportions changed simultaneously upon various P concentrations. For both carbohydrate and lipid proportions in cells, P deficiency was a more effective trigger than alteration in source or concentration of N. Sufficient NP supplies contributed to the productivity of protein and carbohydrate, but not of lipid. Among different N source, NH4Cl caused the lower carbohydrate productivity than NaNO3 and urea. In a one-step cultivation strategy for D. sauna, the economical NP concentrations were suggested as 882.46 and 32.05 mu mol L-1 aiming at protein production, and as 64.10 mu mol L-1 or 48.07 mu mol L-1 at carbohydrate or lipid production, respectively. Two-step cultivation strategy was proposed for aims at lipid production, and the biomass production step at 882.46 mu mol L-1 N and 64.10 mu mol L-1 and the lipid accumulation step at 4.01 mu mot L-1 were suggested.