Researchers engineer bacteria capable of consuming tumours from the inside out. Bacteria spores enter the tumour, finding an environment where there are lots of nutrients and no oxygen, which this organism prefers, and so it starts eating those nutrients and growing in size.

**Researchers engineer bacteria capable of consuming tumours from the inside out**

A research team led by the University of Waterloo is developing a novel tool to treat cancer by engineering hungry bacteria to literally eat tumours from the inside out.

“**Bacteria spores enter the tumour, finding an environment where there are lots of nutrients and no oxygen, which this organism prefers, and so it starts eating those nutrients and growing in size**,” said Dr. Marc Aucoin, a chemical engineering professor at Waterloo. “So, we are now colonizing that central space, and the bacterium is essentially ridding the body of the tumour.”

Key to the approach is a bacterium called Clostridium sporogenes, which is commonly found in soil and can only grow in environments with absolutely no oxygen.

The core of a solid, cancerous tumour is comprised of dead cells and is oxygen-free, making it an ideal breeding ground for the bacterium to multiply.

But there is a biological catch: when the cancer-eating organisms reach the outer edges of tumours, they are exposed to low levels of oxygen and die without completing their mission to fully destroy them.

To solve that problem, the researchers first added a gene to the organism from a related bacterium that can better tolerate oxygen, enabling it to live longer near the outside of a targeted tumour.

They then found a way to activate the oxygen-resistant gene at just the right time – critical to preventing bacteria from inadvertently growing in oxygen-rich places such as the bloodstream – by leveraging a phenomenon known as quorum sensing.

In simple terms, quorum sensing involves chemical signals released by bacteria. Only when many bacteria have grown in a tumour is the signal strong enough to turn on the oxygen-resistant gene, ensuring it doesn’t happen too soon.

For those interested, here’s the link to the peer reviewed journal article:

https://pubs.acs.org/doi/10.1021/acssynbio.5c00628

Good writeup. The paper looks to be about marrying the communication systems the bacteria use around population density and the system that actives dormant genes in the bacteria to make it a little more oxygen tolerant.

I fail to see how that changes anything. We have plenty of ways to kill large tumors – surgery, for one, has been reliable for decades, but that’s not even counting radiotherapy, gamma knife, ablation, cryoablation, and so forth. The challenge of curing cancers lies on their metastatic potential, and the difficulty of dealing with widespread microscopic disease.

Sure, you could say this sort of therapy can kill the tumour in cases where sensitive tissues around it would be too affected by other therapies, but I still don’t see how having a huge infected tumour inside you could be a good thing