Researchers discovered a new agent in horse dung-grown fungi that could be used as an antibiotic.

The protein, dubbed cospin, has the same bacteria-killing effect as antibiotics, but belong to a different biochemical class, ETH Zurich reported. The potential antibiotic substitute was found in the mushroom cap of the Coprinopsis cinerea, which grows in horse dung.

Researchers cultivated the fungus in a laboratory along with several types of bacteria, and found it was able to kill them off.

The team found copsin can bind to lipid II, a building block for cell wall bacteria; If the protein does bind to the lipid the bacteria are no longer able build new cell walls and die.

"Whether copsin will one day be used as an antibiotic in medicine remains to be seen. This is by no means certain, but it cannot be ruled out either," said Markus Aebi, Professor of Mycology.

Even if the substance is never used as a substitute for antibiotics, the findings could provide insight into how fungi use defensins (a group of small proteins that fight microorganisms ) to protect themselves while keeping resistance at bay.

"Fungi have internal instructions on how to use these substances without resulting in selection of resistant bacteria. How to decode these instructions is an intriguing problem for basic research," Aebi said.

The researchers are currently looking at potential applications of copsin, which has been registered for patient approval. The protein is extremely stable, making it less susceptible to degrading enzymes and high temperatures. It can be heated at a temperature of 100 degrees Celsius for several hours. The researchers believe the protein has these exceptional qualities because it has a compact three-dimensional structure.

Copsin could also have applications in the food industry because it can kill contaminating pathogens such as Listeria.

The findings were published in a recent edition of the Journal of Biological Chemistry,