US Patent 7232666 Optimized bacterial host strains of

Methanotrophic bacterial strains are provided that have been optimized for the production of carotenoid compounds through the down-regulation of one or more of the crtN1, ald, crtN2 and crtN3 genes of the carotenoid biosynthetic pathway. The resulting strains lack pigmented C30 carotenoid compounds, and show an increase in the production of C40 carotenoids. The use of the optimized host strains for the production of the C40 carotenoids canthaxanthin and astaxanthin is also described.