Production in Cell Biomass and Carotenoids under the Effect of a Saline Stress in Microalgae Dunaliella spp. Isolated from Moroccan Saharian Saline

Abstract

Microalgae contain a battery of bioactive molecules such as carotenoids used in various industrial sectors. This is the case of the microalga Dunaliella spp., whose cells, under stress conditions, accumulate remarkable levels of carotenoids. In this study, three native strains of Dunaliella (D. viridis (DUN4), D. salina (DUN5) and D. salina (DUN6)) isolated from the Moroccan saharian saline on the Atlantic coast were subjected to different salinity regimes (0.5, 1.5, 2.5, 3.5 and 4.5 M NaCl) to evaluate the ability to produce biomass and carotenoid biosynthesis in this species. Total carotenoids were determined by spectrophotometry. The strains are cultured for 15 days on F/2 Guillard medium and aerated at 25±1°C. Strain DUN5 showed, in the presence of 2.5 M NaCl, a maximum of carotenoids of the order of 3.267μg.ml-1, 3,206μg.ml-1 in the strain DUN 4 to 3.5 M NaCl, and 2,314μg.ml-1 in the strain DUN 6 at 0.5 M NaCl. The highest cell densities are recorded in the strain DUN 4 being of the order of 3.199.106 Cells.ml-1, the concentrations remains lower in the strains DUN5 and DUN6. These results indicate that each strain has a different behavior and physiological response to salt stress. Moreover, these microalgae have remarkable capacities and can constitute a potential source of biochemical molecules of industrial interest.