Abstract: A method to increase carotenoid production in carotenogenic microbial host cells is provided by down-regulating or disrupting glycogen synthesis. Disruption of glycogen synthase activity in a carotenogenic microbial host cell significantly increased carotenoid production. Carotenogenic microorganisms are also provided that have been optimized for the production of carotenoid compounds through the down-regulation and/or disruption of glycogen synthase activity.

Abstract: 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.

Abstract: A method to increase carotenoid production in carotenogenic microbial host cells is provided by down-regulating or disrupting glycogen synthesis. Disruption of glycogen synthase activity in a carotenogenic microbial host cell significantly increased carotenoid production. Carotenogenic microorganisms are also provided that have been optimized for the production of carotenoid compounds through the down-regulation and/or disruption of glycogen synthase activity.

Abstract: The present method is useful for the identification of genes, ORF's and other nucleic acid molecules which are essential for the expression of a specific phenotype in microorganisms. The method employs In vitro transposition in conjunction with an chromosomal integration vector containing a specific gene or genetic element whose function is unknown. Subsequent transformation of a recombination proficient host with the vector and growth first under non-integrating conditions and then under integrating conditions, followed by a selection screen for either single or double crossover events results in transformants that may be subjected to phenotypic screens to determine gene function.

Abstract: The present method is useful for the identification of genes, ORF's and other nucleic acid molecules which are essential for the expression of a specific phenotype in microorganisms. The method employs In vitro transposition in conjunction with an chromosomal integration vector containing a specific gene or genetic element whose function is unknown. Subsequent transformation of a recombination proficient host with the vector and growth first under non-integrating conditions and then under integrating conditions, followed by a selection screen for either single or double crossover events results in transformants that may be subjected to phenotypic screens to determine gene function.