Engineered Bacteria That Eat Tumours From the Inside Out

Bacteria Designed to Devour Cancer

A research team at the University of Waterloo has engineered a common soil bacterium to infiltrate solid tumours and consume them from within, potentially offering a non-surgical route to destroying cancerous growths. The work, published in ACS Synthetic Biology, represents the latest milestone in a decade-long effort to turn microbes into precision cancer-fighting tools.

At the heart of the approach is Clostridium sporogenes, a bacterium that thrives only in oxygen-free environments. The dead, oxygen-starved cores of solid tumours provide an ideal niche for the organism to germinate, multiply, and feed on nutrients within the tumour, breaking it down from the inside.

Overcoming the Oxygen Barrier

The key challenge has been that as the bacteria consume their way outward, they encounter low levels of oxygen at the tumour's edges and die before finishing the job. To solve this, the team introduced a gene from a related bacterium, a water-forming NADH oxidase called noxA, that allows the engineered microbe to tolerate oxygen and survive longer near the tumour's outer regions.

A Genetic Safety Switch

A second innovation addresses safety. The researchers built a quorum-sensing circuit, a natural bacterial communication system where chemical signals grow stronger as the population increases. The oxygen-tolerance gene only switches on once enough bacteria have gathered inside the tumour, preventing premature activation in oxygen-rich environments like the bloodstream.

What Comes Next

The two components have so far been developed and validated separately. The team now plans to combine them in a single organism and test the integrated system in pre-clinical trials. If successful, the approach could one day complement or even replace surgery for certain solid tumours.