A fascinating article on a possible new treatment to fight cancer being researched and developed by our Canadian friends at the University of Waterloo in Ontario, Canada. This from Newsweek.
Team of Scientists Engineer Bacteria That Could Eat Cancer From Inside Out
Engineered bacteria that eat tumors from the inside out could provide a new approach in the fight against cancer, report researchers from the University of Waterloo in Ontario, Canada.
The method is designed to exploit a key weakness in solid cancers—the oxygen-free core that forms as tumor cells die and outgrow their blood supply.
The researchers are working with a bacterium called Clostridium sporogenes, which is commonly found in soil and can only survive in environments that contain no oxygen.
The latter makes the center of many solid tumors an ideal place for the organism to grow. Once inside, the bacteria can multiply and begin breaking down and defeating cancerous tissue from the inside out.
The idea builds on long-standing scientific interest in using bacteria to target tumors, but the Waterloo-led team is attempting to solve a problem that has limited earlier efforts.
While C. sporogenes thrives deep inside tumors, it cannot survive near the outer edges, where small amounts of oxygen are present. As a result, the bacteria die before they are able to fully destroy the tumor and finish the job.
The researchers’ solution involves genetic engineering.
They added a gene from a related bacterium that allows Clostridium sporogenes to better tolerate oxygen. This modification helps the bacteria survive longer as they move closer to the tumor’s outer regions, where oxygen levels are slightly higher.
However, giving the bacteria the ability to tolerate oxygen created a new risk. If the gene were active too early, the bacteria could potentially survive in oxygen-rich parts of the body, such as the bloodstream, where they are not intended to grow.
To prevent that, the team turned to a natural bacterial communication system known as quorum sensing. This relies on chemical signals released by bacteria as they grow and multiply. When only a small number of bacteria are present, the signal remains weak. Once the population reaches a certain size, the signal becomes strong enough to activate specific genes.
In this case, the oxygen-tolerance gene is designed to switch on only after a large number of bacteria have already gathered inside the tumor. This timing ensures that the bacteria remain inactive in oxygen-rich environments and only gain their added survival ability once they are safely established within the cancer.
“Bacteria spores enter the tumor, finding an environment where there are lots of nutrients and no oxygen...we are now colonizing that central space, and the bacterium is essentially ridding the body of the tumor," paper author and chemical engineer professor Marc Aucoin said in a statement.
In their earlier work, the researchers demonstrated that C. sporogenes can be genetically modified to tolerate oxygen. In a follow-up study, they tested their quorum-sensing system by engineering the bacteria to produce a green fluorescent protein. The glow allowed the scientists to confirm that the gene activation occurred only when bacterial numbers reached the desired level.
The next step is to combine both advances—the oxygen-resistant gene and the quorum-sensing control system—into a single bacterium. The team plans to test this engineered organism in pre-clinical tumor models to see whether it can more completely break down solid cancers.
If successful in future testing, the engineered bacteria could offer a highly targeted way to weaken or destroy tumors from the inside.
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Reference
Sadr, S., Zargar, B., Aucoin, M. G., & Ingalls, B. (2025). Construction and Functional Characterization of a Heterologous Quorum Sensing Circuit in Clostridium sporogenes. ACS Synthetic Biology, 14(12), 4857–4868. https://doi.org/10.1021/acssynbio.5c00628
Sadr, S., Zargar, B., Aucoin, M. G., & Ingalls, B. (2025). Construction and Functional Characterization of a Heterologous Quorum Sensing Circuit in Clostridium sporogenes. ACS Synthetic Biology, 14(12), 4857–4868. https://doi.org/10.1021/acssynbio.5c00628
