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.