Most adults, especially considering what happened 5 years ago, now understand at least a little of how the human immune system works.

But a new study out of Israel has demonstrated that even after 120 years of research, there was a whole new component of that system which is now being theorized as a “gold mine” of potential antibiotics.

Inside each of our cells, the discovering team explains in their study, a tiny structure called a proteasome recycles damaged and dead proteins to make new ones, a vital and normal function of cellular repair and maintenance. However, the proteasome has another responsibility that immunologists have never identified: fighting off bacterial infections.

When infected by a bacteria like Salmonella for example, the proteosomes start turning those damaged proteins into weapons—immune compounds that rip into the external membrane of bacterial cells and kill them.

“We discovered a novel mechanism of immunity that is allowing us to have a defence against bacterial infection,” Professor Yifat Merbl, from the Weizmann Institute of Science, told the BBC’s James Gallagher on his team’s discovery. “It’s happening throughout our body in all the cells, and generates a whole new class of potential natural antibiotics.”

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Once the team identified the proteasome’s immune function, they tested the compounds it made on mice with pneumonia and sepsis. They found results similar to some established antibiotics. If their proteasome were inhibited, the mice were easier to infect with Salmonella.

Dr. Lindsey Edwards, a senior lecturer in microbiology at King’s College London told the BBC that because these proteasome-derived antimicrobials are made within us, any trials to test antibiotics based on these compounds would likely achieve safety requirements much faster.

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“In previous years it’s been digging up soil [to find new antibiotics], it is wild that it’s something we have within us, but comes down to having the technology to be able to detect these things,” Dr. Edwards said.