These New GMOs Need Artificial Compounds to Live

If most objections to genetically engineered organisms are based on visceral discomfort rather than scientifically proven safety issues, the news that researchers have gone beyond gene swapping to "actually rewriting the language of genetics," as Richard Harris reports for NPR, might not be comforting. But new "designer bacteria" are actually a proof-of-principle experiment for a way to keep GMOs on a tighter leash.

Most GMOs—whether crops carrying proteins that repel pests or bacteria modified to produce pharmaceuticals—have one or several genes from another organism swapped into place in their genome. One concern about this technology's impact is that modified organisms could escape and propagate in nature, perhaps altering the ecosystem in unexpected ways. 

The E. coli bacteria modified in this experiment would have a hard time doing that. Harris reports:

The enzymes and other proteins in our bodies are all built from building blocks called amino acids. There are usually just 20 amino acids in nature. But George Church, a professor of genetics at Harvard Medical School, has created a bacterium that requires an additional amino acid, one made in the lab and not found in nature. His lab did that by rewriting the bacteria's genetic language to add a "word" that calls for this unnatural amino acid.

"So this really makes it a completely new branch of life," Church says.

These modified E. coli bacteria essentially speak a different genetic language from all other life on Earth. That means they can't easily swap genes, which bacteria often do to pick up or get rid of traits. And it also means that these modified E. coli must be fed the synthetic amino acid to survive.

Both Church’s group and another group created versions of these "designer bacteria." The work was published in two different papers in Nature. 

The idea that modified organisms can be safely contained if they rely on a human-provided substance to survive isn’t new. In fact, the dinosaurs in Jurassic Park were supposed to be controllable because their ability to produce the amino acid lysine had been compromised. Without supplements, the dinos would die. But in the sequels, of course, the canny critters were able to survive by eating lysine-rich chickens and soya beans. The Jurassic Park Wiki points out that the so-called lysine contingency is useless: In real life, no animals produce lysine (that’s why we call it an essential amino acid) and eating lysine-rich food is the only way we all survive.

Fortunately the scientists behind these GMOs are a bit more skilled in basic biology than the sci-fi scientists of Jurassic Park. Church’s group, for example, took into account the fact that bacteria frequently mutate and might lose the code-rewrite that makes them dependent on a synthetic nutrient. The group changed more than one trait to reduce the chance of the bacteria surviving outside of human control. The changes also made the bacteria easier to work with — they are resistant to viruses that often attack bacteria. 

"[T]he newly designed organisms could be safe enough to use outside, for example to clean up oil spills or break down toxic chemicals on contaminated land," writes Ian Sample for the Guardian. "Other bugs based on the same procedure might be put in drinks as probiotics to cure diseases."

A safer new world of synthetic biology might be on the horizon. Maybe just stay away from dinosaurs.

Maris Fessenden | | READ MORE

Maris Fessenden is a freelance science writer and artist who appreciates small things and wide open spaces.