Critics of genetic engineering have long worried about the risk of modified organisms escaping into the environment. A biological-containment strategy described this week in Nature1, 2 has the potential to put some of those fears to rest and to pave the way for greater use of engineered organisms in areas such as agriculture, medicine and environmental clean-up
Two US teams have produced genetically modified (GM) bacteria that depend on a protein building block — an amino acid — that does not occur in nature. The bacteria thrive in the laboratory, growing robustly as long as the unnatural amino acid is included in their diet. But several experiments involving 100 billion or more cells and lasting up to 20 days did not reveal a single microbe capable of surviving in the absence of the artificial supplement.