A bacterium that was supposed to die, then did not

It was dead. Then, in a very modern piece of scientific audacity, researchers brought it back by replacing its DNA with that of another species. The result is being described as the first “zombie bacterium,” and it marks a notable step in synthetic biology, which for decades has been trying to engineer microorganisms so they can carry out functions that do not exist in nature, such as acting as factories for drugs or biofuels.

The study is currently available on bioRxiv, the preprint platform that hosts research before it has been reviewed by the wider scientific community. It comes from Craig Venter, a pioneer in synthetic life research, and the San Diego institute that bears his name.

Why this matters

This is the first time DNA from another species has been transferred into a bacterium. Until now, bacteria had only been modified using DNA from the same species. That distinction may sound like a detail only a molecular biologist would lose sleep over, but in this field details are the entire point.

The newly reported result is the endpoint of a path that began more than 15 years ago, when a Venter-led team produced the first synthetic cell. Back then, researchers built the genome of the bacterium Mycoplasma mycoides on a computer, synthesized it, made it resistant to an antibiotic, and then transplanted it into living bacteria of a closely related species, Mycoplasma capricolum.

The problem researchers wanted to solve

Progress did not stop after that, but it also did not go far enough. One major obstacle was the lack of a reliable way to check whether the new synthetic DNA was actually active once inserted into a cell.

So the researchers took a rather final approach: they modified the bacteria so they could not reproduce. As Zumra Peksaglam Seidel, one of the authors and a synthetic biologist at the J. Craig Venter Institute (JCVI), put it: “They are destined to die, but we bring them back to life.”

The team has nicknamed these organisms “zombie cells,” because apparently ordinary terminology was not going to be dramatic enough for synthetic biology.

What comes next

The researchers now hope to use the same technique in other bacterial species. Another ambition is even more forward-looking: using zombie bacteria to test the function of genomes designed with the help of artificial intelligence.

If that sounds ambitious, it is. But this field has never been accused of thinking small.