Effect of Nitrogen deficiency and light intensity on the fatty acid composition of Chaetoceros calcitrans

Marine diatoms are important sources of fat and fatty acids that are considered for aquaculture and alternative energy sources, and under varying environmental conditions in algae. In order to influence the nitrogen deficiency and light intensity of the medium culture on the C.calcitrans fatty acid composition, algae was exposed to 4 nitrogen treatments (25,50,75 and 100% nitrogen) and light intensity (80, 160, 240 µmol m-2 s-1) in 1 liter Erlenmeyer was cultured. Sampling to determine fatty acid composition was done by harvesting in stationary phase and by Gas-chromatography. The results showed that total saturated fatty acids, C14:0  (Myristic acid), C16:0 (Palmitic acid), and mono unsaturated fatty acids, C16: 1n-7(Palmitoleic acid), C16: 1n-9(Hexadecenoic acid) and C18: 1n-9 (Oleic acid) were decreased by enhancing media nitrogen concentration (P≤0.05). Poly unsaturated fatty acids and also EPA and DHA fatty acids by enhancing nitrogen concentration were increased. Saturated fatty acids, C16:0 (Palmitic acid), C18:0 (Stearic acid), mono unsaturated fatty acids and C16: 1n-7 increased significantly with light intensity enhancement (P≤0.05). Poly unsaturated fatty acids did not show significant difference with light intensity enhancement. Also, the amount of DHA fatty acids did not show significant changes with light intensity, but the EPA increased significantly in the treatment of (240 µmol m-2 s-1) compared to 2 showed another light intensity (80 and 160 m-2 s-1). The overall results showed that unsaturated fatty acids increased with increasing nitrogen concentration in the medium culture, but did not increase fatty acids with increasing light intensity. Conversely, with increasing nitrogen concentration, saturated fatty acids decreased and with increasing light intensity saturated fatty acids increased.