Identification of two species of the green algae Dunaliella and comparing their response to salinity

Abstract

Responses of three species of Dunaliella, viz., D. viridis and D. bioculata, isolated from Shahdad salt river and Sirjan Kafeh Namak watershed (in Kerman province of Iran) and D. maritima obtained from the Center of Biotechnology, Gheshm, Iran was compared at two levels of salinity. The amount of carotenoid, glycerol, reducing sugar and protein in three species were measured under 2 and 4 M NaCl. Algae growth decreased as the medium salinity increased from 2 to 4 M. The amount of glycerol increased considerably in the three species with increase in salinity. Furthermore, the cell color of these species changed from green to orange-red with increasing in salinity. Total carotenoids and β-carotene content decreased with salinity, though high β-carotene content was observed at 2 M NaCl concentration in D. viridis. All the three species showed significant decrease in amount of reducing sugar under salinity from 2 to 4 M NaCl, especially in D. viridis, while the protein content increased. It appears that the pathway of gelycerol production in species of Dunaliella is unique and Iranian species may be suitable for gelycerol and protein production.