PRODUCTION AND SELECTION OF HIGH β‐CAROTENE MUTANTS OF DUNALIELLA BARDAWIL (CHLOROPHYTA)¹

We describe a procedure for the selection of β‐carotenerich mutants of the halotolerant alga Dunaliella bardawil Ben‐Amotz & Avron. Under normal growth conditions the isolated mutants had a several‐fold higher content of β‐carotene than the wild type. Under carotene‐induction conditions, the mutants also possessed a higher β‐carotene content than the wild type. Both the production rate of phytoene and the conversion rate of phytoene to lycopene and β‐carotene were accelerated in the mutants. Cycloheximide, which (in the wild type) inhibits the inductive synthesis of the proteins required for β‐carotene production, had a much smaller effect on β‐carotene biosynthesis in the mutants. We suggest that the mutants are affected in the regulatory path, which controls the induction of high β‐carotene production in Dunaliella .