Microorganisms can be used to synthesise many different products, especially pharmaceuticals and complex biomolecules.
Penicillin, synthesised industrially by engineered Penicillium chrysogenum, is one of the most widely used antibiotics. This can be synthesised industrially with the penicillin secreted into the growth media and then recovered at the end of the growth phase.
Vitamin B12 is synthesised in genetically engineered E. coli, with the complex biosynthetic pathway being introduced into the chassis. This allows the synthesis of an exogenous molecule, with high efficiency. Vitamin B12 is a necessary supplement for individuals that do not consume adequate levels through their diet, as it is not synthesised by eukaryotes. The high replication rate of E. coli also helps increase the synthesis yield, reducing costs. This biosynthesis process used metabolic engineering techniques, allowing the flux through the pathway to be specifically increased in a short period of time.
Lysine is synthesised by Corynebacterium glutamicum, using similar metabolic engineering techniques to expressing vitamin B12 in E. coli (above). Removing feedback inhibition enables higher levels of lysine synthesis to occur compared to the endogenous pathway. Changing and engineering promoters increases expression of synthetic enzymes, allowing for greater flux through previously limiting stages of the pathway. Increasing the concentrations of cofactors by engineering their synthetic pathways also increases the rate of lysine production. Upregulating the expression of lysine transporters (LysE) enables lysine to be moved outside the cell, making further synthesis possible and making it easier to recover from the growth media.