Scientists create self-destructing GM microbes that need artificial compounds to live

In a drive to improve the environmental safety of genetically modified organisms, scientists have created the first GM microbes that can only survive in the presence of designer compounds not found in nature.

The work represents a major step towards the creation of GM lifeforms that are completely reconfigured to perform an important job and then die without trace when their task is done.

Vats of GM microbes are already used to make various chemicals, drugs and dairy products, but the 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. Other bugs based on the same procedure might be put in drinks as probiotics to cure diseases.

Scientists at Harvard and Yale universities made changes throughout the genome of E coli bugs to make them resistant to viruses and reliant upon designer amino acids to survive. Amino acids are the building blocks of proteins that the organisms need to live and multiply.

The researchers call the new microbes “genetically recoded organisms”, or GROs, because they have a new kind of genetic code that ensures they can only thrive when they are fed the synthetic amino acids.

A similar procedure could be used to improve GM crops, but the task is far tougher because plants have about 10 times as many genes that are used to make proteins.

Scientists have created GM bugs before that need a particular chemical to survive, but the safety mechanism has always been vulnerable. The bugs might find the chemical in the environment, pick up DNA from other microbes that lets them use other nutrients, or mutate into a form that can survive without the chemical.