The present invention provides genetically manipulated cells and methods for utilizing same. Methods of enhanced carotenoid synthesis utilizing cells genetically disrupted for a yjiD, hnr or yjfP gene, or further disrupted for a gdhA, gpmB aceE, ppc, talB or fdhF gene, or any combination thereof, or cells inhibited for their expression, activity or function are disclosed. Methods of enhanced carotenoid synthesis utilizing cells genetically engineered to overexpress dxs, idi, yjiD, rpoS, torC, appY, ydgK, yeiA, yedR, tort, arcB, yggT, purDH, yfjN or a combination thereof, or further disrupted for the above-referenced genes are disclosed. Methods for identifying genes involved in optimized production of a carotenoid, and cells disrupted for, or inhibited for the expression, activity or function of genes thus identified are described.