Accumulation of Lipids and Triglycerides in Isochrysis galbana Under Nutrient Stress

This study examines the relationship between the algal biomass as well as lipid and triglyceride contents in Isochrysis galbana and variation in nutrient culture conditions such as phosphorus concentration and iron concentration. From the selected experiments, a clear algal growth drop expressed by number of cells, optical density and dried weight, as well strongly participated in the lipid and triglyceride cumulation, which show a positive significant effect on lipid productivity and triglyceride productivity. In the first experiment of this study, the phosphorus concentration in the medium was reduced to 75%, 50%, and 25% and complete absence (0%) of the original concentration in Walne's medium, whereas the iron concentration was kept constant in the medium. The next experiment, the optimum phosphorus concentration (25%) granting high lipid product was tested with different concentrations of iron from 100 to 0% with five concentrations. Though, the algal growth nonsignificant affected, abundant increases in lipids and triglyceride contents (49.5% and 14.7% of dry weight respectively) was noticed at the concentration of phosphorus of culture medium was decreased to (25%). However, hyperaccumulations of lipid and triglyceride (60.3% and 18.4% on the basis of dry weight, respectively) were acquired by the incorporation of 25% phosphorus and 25% iron. The simple regression analysis suggested the combination effect of phosphorus limitation and iron deprivation on lipid and triglyceride cumulation, and it was not as substantial as to phosphorus starvation tension.