Researchers at Harvard Medical School, led by George Church, have developed an effective method of ‘bio-containment’, preventing a strain of E. coli from growing outside the laboratory. The genome of the bacteria was altered so that their survival depends on a synthetic amino acid.
Genetically modified organisms have proved essential in the agricultural, pharmaceutical and fuel industries. However, the consequences of such organisms escaping the lab might cause detrimental damage to the frail balance of ecosystems.
“We now have the first example of genome-scale engineering rather than gene editing or genome copying,” said Church, a professor of genetics at Harvard Medical School. “This is the most radically altered genome to date in terms of genome function. We have not only a new code, but also a new amino acid, and the organism is totally dependent on it.”
The unnatural amino acid is essential for the translation and correct folding of proteins that are responsible for vital biological processes. Unlike in previous experiments in which bacteria were turned into auxotrophs – organisms, incapables of synthesising nutrients crucial for life, in this research the amino acid incorporated into E. coli’s genome is not found in nature and is only available in labs. The number of bacteria that managed to survive in a medium lacking the key protein building block was so minute that it was impossible to detect.
Apart from being dependent on synthetic nutrients, the modified E. coli strain is also resistant to two viruses. This research suggests that organisms could be made dependent on more than one synthetic nutrient so that it is virtually impossible for them to break out of the lab.