A new part of the immune system that is a goldmine for potential antibiotics has been discovered, scientists say.

They have shown that a part of the body known for recycling proteins has a secret mode that can dump an arsenal of bacteria-killing chemicals.

Researchers in Israel say this is changing our understanding of how we protect ourselves from infections, the BBC reports.

And it gives new room for the search for antibiotics to tackle the growing problem of superbugs that are resistant to our current drugs.

The discovery is linked to the proteasome, a tiny structure found in every cell of the body.

Its main role is to break down old proteins into smaller pieces so that they can be recycled to make new ones.

But a series of experiments detailed in the journal Nature shows that the proteasome recognises when a cell is infected by bacteria.

It then changes its structure and role. It begins to transform old proteins into weapons that can tear apart the outer layer of bacteria to kill them.

"This is really exciting because we never knew this was happening. We have discovered a new mechanism of immunity that allows us to have protection against bacterial infection. This happens throughout our body in all cells and generates a whole new class of potential natural antibiotics," said Professor Ifat Merble from the Weizmann Institute of Science.

The research team went through a process they call "dumpster diving" to discover these natural antibiotics.

They were tested on bacteria growing in the lab and on mice with pneumonia and sepsis. The researchers say they got results comparable to those of some established antibiotics.

And when the scientists took cells into the lab and deactivated the proteasome, they were much easier to infect with bacteria like salmonella.

Professor Dr Daniel Davies, head of the life sciences department and immunologist at Imperial College London, said the findings were "extremely provocative and very interesting" as they change our understanding of how our bodies fight infections.

"What's really exciting about this is that this is a completely undiscovered process by which antigenital molecules are produced in our cells, it feels deeply important and surprising," he said.

But Prof. Davies cautioned that turning this process into a new source of antibiotics is an idea that "still needs to be tested" and that will take time.

It is estimated that more than a million people a year die from infections that are resistant to drugs such as antibiotics.

But despite the need, research to develop new antibiotics to meet the demand is lacking.

Against this bleak backdrop, the availability of a new place to look is a source of optimism for some scientists.

"This is a potential gold mine for new antibiotics, which is quite exciting. In previous years, the ground has been dug (to find new antibiotics), it's wild that this is something we have in house, but it comes down to having the technology to be able to find these things," said Dr Lindsay Edwards, senior lecturer in microbiology at King's College London.

She also explained that there may be fewer problems with developing them into drugs as they are already products of the human body, so "safety may be much easier". | BGNES