Engineering of geranylgeranyl pyrophosphate synthase levels and physiological conditions for enhanced carotenoid and astaxanthin synthesis in

International audience; The basidiomycetous yeast, is one of the very few organisms which can be used for biological production of the carotenoid astaxanthin. cDNA has been cloned from this fungus for engineering of the terpenoid pathway. The function of its gene product as a geranylgeranyl pyrophosphate synthase was established. was transformed with the cDNA to divert metabolite flow from the sterol pathway towards carotenoid biosynthesis. Transformants were obtained with increased levels of geranylgeranyl pyrophosphate synthase leading to higher carotenoid levels including astaxanthin. Physiological conditions for maximum carotenoid synthesis for wild type and the CrtE transformant were dim light and extra air supply of the shaking culture. These conditions and the transformation with had additive effects and resulted in an 8-fold higher astaxanthin formation as compared to the initial wild type culture without illumination and extra air supply yielding 451 μg/g dry wt within 4 days of growth.