1.14.15.24 nutrition engineering of Yarrowia lipolytica for de novo production of the food and feed additive astaxanthin by fermentation. The astaxanthin-producing Yarrowia lipolytica shows great promise for employment in biological astaxanthin production. The genes for beta-carotene biosynthesis: bi-functional phytoene synthase/lycopene cyclase (crtYB) and phytoene desaturase (crtI) from Xanthophyllomyces dendrorhousa are introduced. The activities of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG1) and geranylgeranyl diphosphate synthase (GGS1/crtE) in the best producing strain are optimized. Downregulation of the competing squalene synthase SQS1 increases the beta-carotene titer. Then a beta-carotene ketolase (crtW) from Paracoccus sp. N81106 and hydroxylase (crtZ) from Pantoea ananatis are introduced to convert beta-carotene into astaxanthin. The constructed strain accumulates 10.4 mg/l of astaxanthin but also accumulates astaxanthin biosynthesis intermediates, 5.7 mg/l canthaxanthin, and 35.3 mg/l echinenone. The copy numbers of crtZ and crtW are optimized to obtain 3.5 mg/g dry cell weight (54.6 mg/l) of astaxanthin in a microtiter plate cultivation 749390 1.14.15.24 synthesis synthesis of astaxanthin. Astaxanthin is a carotenoid of significant commercial value due to its superior antioxidant potential and wide applications in the aquaculture, food, cosmetic and pharmaceutical industries. The Brevundimonas sp. SD212 crtW and Pantoea ananatis crtZ genes are the best combination for astaxanthin production. After balancing the activities of beta-carotene ketolase and hydroxylase, an Escherichia coli ASTA-1 that carries neither a plasmid nor an antibiotic marker is constructed to produce astaxanthin as the predominant carotenoid (96.6%) with a specific content of 7.4 mg/g dry cell weight without an addition of inducer 743205 1.14.15.24 synthesis the combination of the foreign bacterial enzyme CrtW and the endogenous carotenoid biosynthesis enzymes for synthesizing antheraxanthin in tobacco plants isable to produce the novel carotenoid 4-ketoantherazanthin 749393