Strain selection for β-carotene production by Dunaliella

Four strains of Dunaliella were grown at 25°C and pH 8±0.5, with continous illumination at 200 W/m². Their maximum specific growth rates ranged from 0.093 day^-1 to 0.234 day^-1, nitrate yields from 3.0 to 7.8 g cells/g NaNO₃ and lipid contents from 3% to 6% of the dry wt, with carotenes 50 to 80% of the lipids. Of the carotenes, β-carotene made up 7 to 19%; all-trans-β-carotene 32 to 52% and 9-cis-β-carotene 29 to 55%. There are, therefore, considerable intra-specific differences between strains of Dunaliella.