New Antibiotic In Mushroom That Grows On Horse Dung

A new antibiotic is discovered in the mushroom Coprinopsis cinerea that grows in horse dung.
A new antibiotic is discovered in the mushroom Coprinopsis
 cinerea that grows in horse dung. (Image source)
Microbiologists and molecular biologists have discovered a new agent in fungi that kills bacteria. The substance, known as copsin, has the same effect as traditional antibiotics, but belongs to a different class of biochemical substances. Copsin is a protein, whereas traditional antibiotics are often non-protein organic compounds. The findings were published in the Journal of Biological Chemistry.
 
The researchers discovered the substance in the common inky cap mushroom Coprinopsis cinerea that grows on horse dung. When they began their research, the scientists were interested in understanding how this fungus and various bacteria affect each other's growth. This involved cultivating the fungus in a laboratory along with several different types of bacteria. It was found that C. cinerea is able to kill certain bacteria. Further research demonstrated that the copsin produced by the mushroom is responsible for this antibiotic effect.

Copsin belongs to the group of defensins, a class of small proteins produced by many organisms to combat microorganisms that cause disease. The human body also produces defensins to protect itself against infections. They have been found, for example, on the skin and in the mucous membranes.
 
The protein is exceptionally stable. Proteins are generally susceptible to protein-degrading enzymes and high temperatures. Copsin is an exception because it also remains stable when heated to a temperature of 100 degrees Celsius for several hours or when subjected to protein-degrading enzymes. The researchers believe that the protein has these properties because of its extremely compact three-dimensional structure, as NMR spectroscopy has shown.
 
The researchers were also able to unravel the exact mechanism of action, discovering that copsin can bind to lipid II, an essential building block for the cell wall of bacteria. If copsin binds to lipid II, the bacteria die because they are unable to build new cell wall.
 
In addition to being used as an antibiotic in medicine, it may also be possible to use copsin in the food industry as well. This is because copsin kills many pathogens including Listeria, a type of bacteria that can cause severe food poisoning and is therefore feared, especially in the production of non-heat treated foodstuffs such as raw milk cheeses and dried meats.