بررسي اثر كمبود نيترات بر تقسيم سلولي و سنتز رنگيزهاي بتاكاروتن و كلروفيل در جلبك سبزتك سلولي DUNALIELLA SALINA جداسازي شده از مرداب شور گاوخوني اصفهان

The effect of nitrate deficiency on cell division and beta-carotene and chlorophyll synthesis in unicellular

Effect of five concentrations of KN03 (zero, 0.5,1.5,5 as a control, 10 mM) in 1 M NaCl on the cell density and content of pigments (betacarotene and chlorophyll) was investigated in Iranian strain of D. salina. The cultures were kept at light intensity of 100 µ mol photon, m-2. s ʹ, light / dark regime of 16/8 hours at 26± 2* The result illustrated, 0.5 mM nitrate in the medium is caused to decreasing of growth, increasing of intracellular beta-carotene. However, at higher concentration of nitrate in the medium no significant changes were observed. In addition, it was revealed that except the medium with no nitrate, at all concentration there is no significant difference in specific growth rate (µ ) of cultures and 10 mm nitrate in the medium had no any negative effect on growth of this strain. As a result, it appeared that nitrate limitation (0.5 mM) arises content of beta-caroten in Iranian strain of D. salina, but this accumulation is lesser than other strains were reported in the literatures. Therefore, it seems, this strain uses replacement pathways for scavenging of free radicals, which probably is produced by nitrate deficiency.