Zombie Bacteria That Keep Building After Death
It sounds like a Halloween story, but the researchers at Aarhus University in Denmark are quite serious: bacteria can continue producing DNA after they die. Or rather, the machinery they leave behind carries on working — and the scientists have found a way to control what it produces. The discovery could eventually contribute to new biological materials, and it raises a fascinating question about why bacteria carry the viruses that make it happen.
Viruses on standby
Bacteria often live in communities called biofilms, surrounded by a sticky substance that contains DNA, among other things. It serves as both building material and protection — the plaque we brush off our teeth is a biofilm. Many bacteria also carry bacteriophages: viruses that infect only bacteria. Some of these viruses lie dormant as part of the bacterium's genetic material, waiting.
The Aarhus team, led by first author Gabriel Antonio Minero of the Department of Biology, starved two bacterial species — Shewanella oneidensis and Bacillus subtilis — of nutrients. That woke some of the dormant viruses, which multiplied and eventually burst their host cells open. You might think that would bring all work to a halt. Instead, when the cells burst, both the building blocks of DNA and specialised 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," says Minero.
Proving the DNA was new
To be sure they were seeing genuinely new DNA rather than remnants of the burst cells, the researchers added a small, artificially made ring of DNA to the cultures. The ring served as a blueprint that the enzymes could copy over and over again through rolling circle replication, producing DNA with a distinctive structure detectable with fluorescent dyes.
Under the microscope, the new 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 — confirming the viruses were essential to the process. Minero calls the bacteriophages "nano-architects": although they kill some of the bacteria, they also supply part of the molecular machinery that keeps building the biofilm.
Zombies with special powers
The team went further than observing the process: they worked out how to change the blueprint and thereby determine which type of DNA the machinery produces. "What matters most to me is that we can hijack the process," says Minero. Among other things, they got the zombie factories to produce G-quadruplexes — DNA structures that fold into particular shapes, allowing them to bind other molecules and act rather like enzymes, speeding up certain chemical reactions. That special DNA could act as a catalyst and alter the biofilm's electrical properties.
The discovery, published in Angewandte Chemie on 29 October 2026, opens intriguing possibilities. DNA is not just a blueprint for life; it can also have chemical properties that make it useful for other purposes. In the longer term, Minero envisions programming the bacteria's DNA production to create different materials that could help break down pollutants — produced wherever they are needed, rather than in a factory. One area of potential interest is environmental biotechnology, where researchers already try to harness bacteria for wastewater treatment and bioenergy production.
There is still a long way to go: the experiments were carried out in the laboratory with two bacterial species and DNA blueprints supplied by the researchers themselves. They have not yet demonstrated that the technology can clean up polluted water or improve bioenergy production. And one puzzle remains: why do some bacteria harbour dormant viruses in the first place? Is it coincidence that the viruses help build the community after killing some of its members — or has this interaction evolved because, under certain conditions, it benefits the bacteria? The researchers cannot yet answer that.
And if all this has left you thinking that bacteria in biofilms are practically immortal, think again: the bacteria really are dead. It is just that some of their machinery has not gotten the message.
If your child loves biology's stranger stories — viruses, DNA and microbes that refuse to quit — a first lesson in biology can take them from this zombie factory to the cell biology behind it, with booster and mock-exam help in biology along the way. Book your first lesson
Sources:
- phys.org, "Zombie bacteria keep building DNA after death", 29 October 2026: https://phys.org/news/2026-10-zombie-bacteria-dna-death.html
- 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
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