Genetic engineering of ketocarotenoid production in soybean
Pierce, Emily Coleen
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Carotenoids are a group of natural pigments that can bioaccummulate and provide color to many animal products. The pink or red ketocarotenoids, canthaxanthin and astaxanthin, are used as feed additives in the poultry and aquaculture industries for egg yolk and flesh pigmentation. Because soybean is an important component in animal feed, production of these carotenoids in soybean would be a more cost-effective mean of delivery. Soybean was transformed with the crtB gene from Pantoea ananatis, which codes for phytoene synthase, the enzyme needed for carotene production in the seed. The crtB gene was engineered with genes encoding ketolase and hydroxylase enzymes to produce additional carotenoids from carotene; all genes were under the control of seed-specific promoters. HPLC results show that the resulting seeds accumulated increased levels of carotenoids. Combinations of carotenogenic enzymes were assayed in E. coli to determine which combinations are the best candidates for future transformation of soybean.