Metabolic engineering is a process for the production of chemicals, fuels, and pharmaceuticals by altering the metabolic pathways of the organisms. This method involves useful alteration of metabolic pathways to better understand and utilize the cellular pathways. Metabolic engineering is motivated by commercial applications by which we can improve the developing strains for production of useful metabolites. This method requires overexpression or downregulation of certain proteins in a metabolic pathway, such that the cell produces a new product. Considering its advantages over the other chemical synthesis routes, this area of biotechnology is likely to revolutionize the way in which commodity chemicals are produced.