Recombinant bacteria are bacteria that have undergone genetic engineering. This means their DNA has been altered by the introduction of new DNA. Such bacteria have been of immense value in biological research, and for industrial and environmental uses.
New DNA is often introduced in some sort of vehicle that is known as a vector. This can be a plasmid or a virus. The plasmid has a type of selectable marker, so that the cells will keep producing it. Often, this is antibiotic resistance. It is also possible to introduce a gene directly into the bacterium’s own DNA.
Often when a new gene is cloned, it is expressed in a microorganism, and frequently in bacteria. The lab rat of the bacterial world is Escherichia coli, commonly found in our intestines. Many strains of E. coli are available for cloning experiments.
Many cloning kits are available that facilitate a high level of expression of protein produced by a cloned gene in E. coli. This is known as overexpression. In basic research, such techniques help provide enough material to study the function and properties of the product of the gene.
Overexpression techniques in recombinant bacteria have been of great utility for various industries. They have enabled the production of materials that are very difficult to isolate from natural sources. Also, isolating compounds from humans risks the spread of diseases. Many proteins of medical importance have been produced commercially in this manner. Insulin, human growth hormone, and the anti-anemia drug erythropoietin are some examples.
Many other species of bacteria are capable of being altered genetically. This includes those that can live in more extreme environmental conditions, such as polluted wastewater. Often the process of making a chemical, or degrading one, takes several different chemical steps. Scientists have been able to engineer some recombinant bacteria with the genes for whole pathways for the biosynthesis, or biodegradation, of compounds.
Genetically-altered bacteria are finding use in bioremediation. This is the practice of using organisms to treat pollution made by humans. For decades, bacteria and fungi have been used to treat wastewater and decontaminate water and soils infused with organic pollutants. With the advent of genetic engineering, however, it is possible to design recombinant bacteria to break down pollutants under conditions that unaltered microorganisms may find unfavorable.
Bacteria are particularly adept at taking up toxic metals. The treatment of contaminated soil and solid waste is generally done in a large tank known as a bioreactor. This is a way of containing the recombinant bacteria, so they do not escape into the environment. It also makes it easier to optimize environmental conditions to those that favor growth of the bacteria. Also, new strains of bacteria can be created to break down compounds that were previously very resistant to degradation.