Converted carotenoid production in Dunaliella salina by using cyclization inhibitors 2-methylimidazole and 3-amino-1,2,4-triazole

Abstract

Carotenoids are vital for most photosynthetic organisms because of their crucial role in prevention of the damage caused by excess light or stress conditions like heat or nutrient deprivation. Some of them are also valuable for biotechnology with respect to their colorful feature and antioxidant properties. In this study, a natural β-carotene producer, green microalga Dunaliella salina, was evaluated for its potential to produce different valuable carotenoids through the inhibition of cyclization reactions in the carotenoid pathway by the chemical inhibitors 2-methylimidazole (2MI) and 3-amino-1,2,4-triazole (Amitrol). 2MI was shown to be effective on lutein accumulation in D. salina cultures grown at high temperature, without affecting cell viability. Addition of 2MI to the culture at 1 mM concentration resulted a 1.7-fold increase in lutein content in the cell with the highest amount of 3.45 pg/cell, and an associated decrease in β-carotene content suggesting that this inhibitor is more effective on lycopene beta-cyclase activity, thus shifting the pathway from β-carotene arm to the α-carotene direction. The results of this study may give the opportunity to use D. salina for the production of valuable carotenoids other than β-carotene.