Cloning and Expression of Heterologus Genes - Introduction of foreign genes may lead to expression of a heterologous enzyme or transport system in any organism leading to the production of new compounds.

However, these new compounds may undergo further reactions which can not be anticipated, thus putting a limitation on its use for metabolic engineering.

Further, the protein thus synthesized may or may not fold properly and may not be suitably localized. Despite these limitations, the number and scope of positive experiments encourage further application of this approach.Following are some of the possible applications of cloning and expression of foreign genes in metabolic engineering.