A mutant of the green alga <i>Dunaliella salina</i> constitutively accumulates zeaxanthin under all growth conditions

Abstract A novel mutant ( zea1 ) of the halotolerant unicellular green alga Dunaliella salina is impaired in the zeaxanthin epoxidation reaction, thereby lacking a number of the β‐branch xanthophylls. HPLC analysis revealed that the zea1 mutant lacks neoxanthin (N), violaxanthin (V) and antheraxanthin (A) but constitutively accumulates zeaxanthin (Z). Under low‐light physiological growth conditions, the zea1 (6 mg Z per g dry weight or 8 × 10 −16 mol Z/cell) had a substantially higher Z content than the wild type (0.2 mg Z per g dry weight or 0.5 × 10 −16 mol Z/cell). Lack of N, V, and A did not affect photosynthesis or growth of the zea1 strain. Biochemical analyses suggested that Z constitutively and quantitatively substitutes for N, V, and A in the zea1 strain. This mutant is discussed in terms of its commercial value and potential utilization by the algal biotechnology industry for the production of zeaxanthin, a high‐value bioproduct. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 81: 115–124, 2003.