As more and more bacteria become resistant to the dwindling arsenal of drugs we possess, there is the very serious threat that we may soon run out of effective antibiotics. This has led to increasing calls to widen our search for novel antibiotics, a pursuit that has led some researchers into the pouch of the Tasmanian devil. It turns out that the devils' milk could help kill antibiotic-resistant bacteria.
While in human milk there is only one type of antimicrobial peptide, called cathelicidins, in Tasmanian devil milk there are least six that the researchers were able to identify. These are thought to be produced not just in the milk of the devils, but also in the lining of their pouch. To test the efficacy of these peptides, the researchers recreated these molecules in the lab and then tested them against 25 different types of bacteria, including the methicillin-resistant Staphylococcus aureus, also known as MRSA.
Published in Scientific Reports, the team of scientists from the University of Sydney found that the cathelicidins from the devils' milk were effective against a number of types of bacteria, including MRSA, as well as against some types of fungi that can lead to infection. It is hoped that more research into these peptides could lead to the development of new antibiotic drugs.
The researchers think that the evolution of the devils’ antibiotic milk is related to their marsupial lifestyle. Newborn pups are typically underdeveloped and crawl into their mother's pouch, where they are then fed milk and continue growing for around four months until they can support themselves. This, however, means that the newborns are living in a bacteria-filled environment, despite the fact that their immune system is not yet fully functioning. To make up for this, it is thought that the mothers pass on increased protection through their milk in the form of the cathelicidins.
But the discovery of these peptides might not only benefit the development of new drugs. The researchers are hoping that they might also have anti-cancer properties, which would be of huge benefit to the devils themselves. Currently, the Tasmanian devil population is being devastated by a contagious cancer that has swept through the population, causing their numbers to crash. Perhaps these new molecules may also confer some sort of resistance and help save the species.
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