Synthetic amino acids may one day allow scientists to create "genetic firewalls" that prevent GMO crops or animals from escaping into the wild and causing environmental damage, according to Harvard and Yale researchers.
On Wednesday, scientists announced that they had genetically engineered bacteria whose very survival depended on lab-formulated amino acids. By "locking in" this synthetic nutritional requirement, researchers said the bacteria would quickly die if they escaped their carefully controlled environment and entered the world at large.
"I don't want to be alarmist or anything, but I think the point is that these organisms do spread," said George Church, a Harvard Medical School genetics professor.
The altered bacteria, which Church and his colleagues dubbed genomically recoded organisms, or GROs, were described in a pair of studies published Wednesday in the journal Nature.
Genetically altered bacteria are used to produce a growing number of products, including pharmaceutical proteins, such as insulin; dairy items, such as yogurt; and polymers used to create textiles.
While it is much easier to alter the genetic coding of bacteria than it is to alter plant and animal genomes, Church said that it was plausible that the technique could be extend to more complicated GMOs, such as crops.
Church and Farren Isaacs - an assistant professor of molecular, cellular and developmental biology at Yale, and the senior author of one of the studies - said their work was motivated by the concern that modified organisms could enter the wild and out-compete natural species. It is this concern that has caused some to heavily criticize the use of GMOs in industry and agriculture.
"It's a scenario," Church told reporters. "You want to get ahead of these things, rather than wait until you have a problem."
The key to designing a fail-safe measure involves amino acids, which bacteria and other organisms use to assemble the multitude of proteins necessary for life functions.
In the natural environment there are only 20 such amino acids, yet cells use this limited palette of chemicals to produce a dizzying array of specialized proteins. The recipe for each of these proteins is encoded in an organism's genome.
In the Harvard study, Church and his colleagues altered the genome of E. coli bacteria so that it contained new instructions for a single, critical protein, but required the man-made amino acid, biphenylalanine, or bipA, to produce it.
"We do consider this a new class of organism," Church told reporters. "It's not just a new species. In a way it's a new kingdom."
It is possible that after reproducing for generations, the altered microbe will eventually develop a mutation that allows it to survive without bipA, Church said.
To guard against this, researchers said they would need to alter the bacteria so that it created a number of essential proteins using synthetic amino acids.
Church and Isaacs said they hoped to make such bacteria attractive to industry by also making the microbes immune to viruses.
"Our next step is to make a truly multi-virus-resistant organism that's resistant to all viruses, even viruses we haven't characterized yet from the wild," Church said.