Abstract
Dunaliella salina is an important microalga for beta-carotene production. In Thailand, the D. salina has not been commercially cultivated. Aim of this study was to screen high beta-carotene producing mutants. D. salina KU11 cells were radiated with 0.4 mmol photons m(-2).s(-1) UV-C for 22 min. After 3 weeks, colonies which survived after radiation were allowed to grow on agar plates; fifty colonies out of 19,720 UV-mutagenized strains turned to orange. These colonies were picked up and transfer to modified Johnson medium. Four mutants out of fifty were KU5, KU18, KU20 and KU37 significantly produced high beta-carotene at the stationary phase approximately up to 1.62, 2.03, 1.32 and 1.21 folds, respectively, compared to the wild type strain. In all three consecutive cycles of cultivation, the mutant KU18 accumulated 2.4-8.5 folds beta-carotene (mu g/ml) and 2.1-4.8 folds beta-carotene (pg/cell) higher than the wild type, whereas cell density of the mutant KU18 was not different from the wild type. This is the new record of b-carotene producing mutant isolated from saline soil in Thailand.
