Scientists Revive Dead Bacteria With Synthetic Genome Transplants, Creating the First Living Cells Built From Non-Living Parts
Researchers at the J. Craig Venter Institute transplanted synthetic genomes into chemically killed bacteria, producing 'zombie cells' that resumed normal growth and division.
Overview
Researchers at the J. Craig Venter Institute (JCVI) in La Jolla, California, have created what they call “zombie cells” — dead bacteria brought back to life by transplanting a complete synthetic genome into them. The technique, described in a preprint posted to bioRxiv on March 13, represents the first time scientists have constructed living, synthetic bacterial cells from non-living parts, and it could open new pathways for engineering microbes that produce drugs, biofuels, and other useful compounds.
What We Know
The team, led by synthetic biologist John Glass, used the chemotherapy drug mitomycin C to damage the DNA of the bacterium Mycoplasma capricolum, as reported by Nature. The treatment left the cells metabolically active but unable to reproduce — functionally dead. The researchers then transplanted a fully synthetic genome from a related species, Mycoplasma mycoides, into these defunct cells using a process called whole genome transplantation (WGT).
A small fraction of the treated bacteria survived, resumed normal growth and division, and genetic tests confirmed that the synthetic genome had taken full control of cellular functions, according to Nature.
The key innovation is what the researchers call a “selection-free” approach. Previous genome transplantation methods relied on antibiotic resistance markers to identify which cells had successfully accepted the new genome. This created a problem: the recipient cell’s own genome could incorporate the resistance genes through homologous recombination, producing false positives. By chemically killing the recipient’s genome first, the JCVI team eliminated this issue entirely — any cell that grows must be running on the transplanted genome, as described in the bioRxiv preprint.
What We Don’t Know
The technique currently works only between closely related Mycoplasma species, and the precise reasons why it succeeds in these cases remain poorly understood, Nature reports. Previous efforts to transplant genomes into more diverse bacterial species have failed, often because researchers could not reliably inactivate the recipient genome.
Glass and his colleagues hope to extend the method to other microbes, including E. coli and yeast, according to Nature. However, these organisms present additional challenges: they have significantly larger genomes and protective cell walls that complicate transplantation.
The efficiency of the process — specifically what fraction of treated cells successfully accept and express the new genome — has not been fully characterized in public reporting of the preprint results.
Analysis
The research builds on decades of work at JCVI, where Craig Venter’s team created the first synthetic bacterial cell in 2010 by assembling a complete 1.1-million-base-pair genome and booting it up inside a living cell. That earlier achievement required a living host, which introduced complications. The new selection-free approach sidesteps this limitation by using dead cells as blank templates, potentially making genome transfer more predictable and scalable.
If the method can be extended beyond Mycoplasma to industrially relevant organisms, it could accelerate the development of engineered microbes for drug production, sustainable fuel synthesis, and environmental remediation. The ability to install entirely new genomes without relying on selection markers would simplify the construction of custom organisms, a long-standing goal of synthetic biology.
For now, the work remains at the preprint stage and will need to pass peer review. The gap between reviving closely related Mycoplasma species and reprogramming the workhorses of industrial biotechnology is substantial, but the selection-free framework offers a clearer path forward than previous approaches.