Regional difference of three strains of Dunaliella, and their carotenogenic capacity

Abstract

The unicellular green alga Dunaliella salina and D. bardawil are well-known microalgae accumulating high levels of beta-carotene under growth-limiting stress conditions. The carotenogenic microalga Dunaliella salina is cultivated as a natural source of beta-carotene. High irradiance appears to stimulate specifically all-trans beta-carotene accumulation in D. salina. We studied the effect of irradiance on the growth and the carotenogenesis of three species (D.salina CCAP19/18, D. bardawil and D. salina KCTC10654BP from Australia, Israel and Korea, respectively) of D. salina cultivated under two photon flux densities (30 and 700 μmol m-2s-1 ) and same temperatures (25℃). Carotenoids (beta-carotene isomers) were measured by HPLC. We tried to identify three green algae by analyses of partial 18S rDNA and two ITS sequences. Partial 18S rDNA sequences are about 900 bp and ITS1 and ITS2 are 296 bp and 420 bp, respectively. As a result of ITS1 and ITS2, Dunaliella salina KCTC10654BP has very similar to D. bardawil based on phylogenic study. In addition, there are differences between D. salina KCTC10654BP, D. bardawil and D. salina CCAP19/18 through the PCR electrophoretic image for partial 18S rDNA.