The use of enzymes that catalyze the production of starter and extender units for polyketides in E. coli and Streptomyces is described; these enzymes include malonyl CoA decarboxylase (MatA), malonyl CoA synthetase (MatB), and a malonate transporter (MatC) as well as proprionyl CoA carboxylase (pcc). The matBC gene from Streptomyces coelicolor, the matABC genes from Rhizobium trifoli, and the pccB and accA2 from Streptomyces coelicolor are useful in specific embodiments of the claimed invention. These enzymes may be used to enhance the yield of polyketides that are natively produced or polyketides that are rationally designed. By using these techniques, the synthesis of a complete polyketide has been achieved in E. coli in the presence of a phosphopantetheinyl transferase, such as sfp from Bacillus subtilis. This achievement permits a host organism with desirable characteristics to be used in the production of such polyketides and to assess the results of gene shuffling.