Response of Dunaliella strains to various salt condition

Abstract

Species of Dunaliella are known to be adaptive to broad range of salinity. We investigated changes in physiological properties of Dunaliella strains in different salinity. In this study, we compared salt response of four Dunaliella strains: Dunaliella. sp, D. bardawil, D. salina Korea, D.viridis, at different NaCl concentration: from 1.5M to 4.5M. Growth patterns in different salinities show difference in salinity adaptation among different Dunaliella strains. D. viridis showed the highest growth rate throughout all the salinity conditions, and was the only strain which grew at 4.5M NaCl. Despite this large difference in growth rate of Dunaliella in different salinity, photosynthetic ability of each strain did not change in different salinities. The low photosynthetic ability of D. viridis was exceptional considering the highest growth rate among the four strains. Immunoblotting assay revealed the differential expression of iron superoxide dismutase(FeSOD) and carbonic anhydrase(CA) in different saline concentration condition. Contrary to our expectation, the antioxidant enzyme FeSOD reduced in higher salt in D. viridis, whereas FeSOD in D. bardawil increased. The level of CA was not affected by different salt concentration.