Some bacteria can keep building DNA even after death!

What?!

Yes, you read it right!

Researchers  have discovered that bacteria can continue producing DNA after they die. And they have found a way to control what gets produced. The discovery could eventually contribute to the development of new biological materials.

This is extracellular DNA (eDNA).
Researchers  have found something that could belong in a horror film: bacteria that continue producing DNA after they are dead. Or rather, the machinery they leave behind carries on working. And behind it all are viruses that both kill the bacteria and provide some of the equipment.

The researchers have even worked out how to get the bacteria's "zombie factories" to produce DNA according to a particular blueprint.
Bacteria often live in communities known as biofilms. They are surrounded by a sticky substance that contains DNA, among other things. It serves as both building material and protection—for example, in the plaque we brush off our teeth.
Many bacteria also carry what are known as bacteriophages—viruses that infect only bacteria. Some bacteriophages can lie dormant as part of a bacterium's genetic material.

The researchers deprived two bacterial species, Shewanella oneidensis and Bacillus subtilis, of nutrients. This caused some of the dormant viruses to wake up and multiply. Eventually, they burst the bacterial cells open.

You might think that would bring all work to a halt.

But when the cells burst, both the building blocks of DNA and specialized enzymes were released. And the enzymes continued making DNA outside the dead bacteria—out in the biofilm.

"In a way, life goes on after the bacterium has died."
To find out whether they were really seeing newly produced DNA—rather than merely remnants of the burst cells—the researchers added a small, artificially made ring of DNA to the bacterial cultures.
The ring served as a blueprint that the enzymes could copy over and over again. The new DNA had a distinctive structure that could be detected using fluorescent dyes.

Under the microscope, the DNA combined with other substances to form shapes resembling flowers in one bacterial species and long strands in the other. And when the researchers used a bacterial strain that lacked the relevant viruses, none of this particular DNA was produced.

The researchers have done more than get the machinery of dead bacteria to produce DNA. They have also worked out how to change the blueprint and thereby determine which type of DNA the machinery produces.

Among other things, the researchers got the zombie factories to produce what are known as G-quadruplexes. These are DNA structures that fold into particular shapes, allowing them to bind other molecules and act rather like enzymes, speeding up certain chemical reactions.

The armour has not, of course, been shown to protect against antibiotics or other attacks. But the researchers have demonstrated that this special DNA can act as a catalyst and alter the biofilm's electrical properties.

The discovery also raises an intriguing question: why do some bacteria harbour dormant viruses in their genetic material?

Is it mere coincidence that bacteriophages can help build on the bacterial community after killing some of its members? Or has this interaction evolved because, under certain conditions, it benefits the bacteria?

The study thus raises many new questions and possibilities for the researchers to explore.

And if all this has left you thinking that bacteria in biofilms are so well protected that they are practically immortal, think again:

The bacteria really are dead. It's just that some of their machinery hasn't gotten the message.

Gabriel Antonio S. Minero et al., Prophage Activation Triggers Extracellular Synthesis of DNA in Bacterial Biofilms via Rolling Circle Replication, Angewandte Chemie International Edition (2026). DOI: 10.1002/anie.3695434

Picture Credit: Gabriel Antonio Minero / Angewandte Chemie