| abstract |
The present invention provides means and methods of transforming bacteria, fungi including yeast, animal and plant cells, seeds, tissues and whole plan ts in order to yield transformants capable of expressing novel .beta.-carotene dioxygenases and accumulating important metabolites of the carotene/retinoid pathway such as vitamin A aldehyde and retinoic acid. The present invention further provides means and methods to biotechnically produce retinoids using cells, tissues, organs or whole organisms which natively or after transformation accumulate .beta.-carotene or which take up .beta.-carotene from the medium. The present invention also provides DNA molecules encoding symmetrically and asymmetrically cleaving .beta.-carotene dioxygenases deriv ed form different sources and taxonomic groups of living organisms designed to be suitable for carrying out the method of the invention, and plasmides or vect or systems comprising said molecules. Furthermore, the present invention provid es transgenic bacteria, fungi including yeast, animal and plant cells, seeds, tissues and whole plants that display an improved nutritional quality or physiological condition and contain such DNA molecules and/or that have been generated by use of the methods of the present invention. |