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Abstract:
The red yeast Xanthophyllomyces dendrorhous is an established platform for the synthesis of carotenoids. It was used for the generation of novel multi oxygenated carotenoid structures. This was achieved by a combinatorial approach starting with the selection of a beta-carotene accumulating mutant, stepwise pathway engineering by integration of three microbial genes into the genome and finally the chemical reduction of the resulting 4,4'-diketo-nostoxanthin (2,3,2',3'-tetrahydroxy-4,4'-diketo-beta-carotene) and 4-keto-nostoxanthin (2,3,2',3'-tetrahydroxy-4-monoketo-beta-carotene). Both keto carotenoids and the resulting 4,4'-dihydroxy-nostoxanthin (2,3,4,2',3',4'-hexahydroxy-beta-carotene) and 4-hydroxy-nostoxanthin (2,3,4,2'3'-pentahydroxy-beta-carotene) were separated by high-performance liquid chromatography (HPLC) and analyzed by mass spectrometry. Their molecular masses and fragmentation patterns allowed the unequivocal identification of all four carotenoids.
