Bacteria as production organisms

Bacteria can be used as living producers of useful molecules. Each bacterial cell has machinery that can build complex molecules, and bacteria reproduce rapidly in suitable conditions. A small starting population can therefore grow into a large population in a short time. With many cells making a molecule, a larger amount can be produced.

Genetic modification can change what a bacterium is able to make. For example, adding a gene containing instructions for a particular protein can enable the bacterium to produce that protein. As the modified bacteria reproduce, a large population of cells can be produced to make the desired molecule.

Bacteria as hosts for genetic modification

Bacteria can act as hosts for genetic modification: they can receive a gene that changes their genetic information. Many bacteria contain plasmids, which are small, circular DNA molecules separate from the main bacterial chromosome.

A gene can be inserted into a plasmid, and the plasmid can then carry that gene into a bacterial cell. The cell therefore gains genetic information that it did not previously contain. The plasmid acts as a carrier of the inserted gene.

Bacteria are also suitable hosts because growing and genetically manipulating them raises relatively few ethical concerns about the treatment of the bacteria themselves. This ethical consideration, together with the availability of plasmids as gene carriers, contributes to their suitability for genetic modification.