Platypuses sweat milk from their bellies — and it could help save us from superbugs, scientists say

A four months old female Platypus ‘puggle’ is weighed at Taronga Zoo in Sydney, Australia.
A four months old female Platypus ‘puggle’ is weighed at Taronga Zoo in Sydney, Australia. ASSOCIATED PRESS

The platypus is about as bizarre and contradictory as animals come.

The semi-aquatic Australian creatures are mammals, but they lay eggs instead of giving live birth. They have bills like ducks, but feet like otters and tails like beavers. And the males are venomous, too, with spurs on their back legs that inflict pain as ferocious as a hundred hornet stings, according to researchers.

But it’s the female platypus (or at least the milk they produce) that new research suggests could be a game-changer for humans — particularly as more and more infections in humans become resistant to traditional antibiotics.

Scientists at Australia’s independent, government-funded research agency have identified the structure of a key protein in platypus milk that gives the unusual mammals’ milk antibacterial qualities — and it’s helped them establish why the animal’s milk has those properties, which the Australian researchers first discovered in 2010.

“Platypus are such weird animals that it would make sense for them to have weird biochemistry,” Dr. Janet Newman, the Australian scientist who led research on the milk, said in a statement.

Her research was published Thursday in Structural Biology Communications, and marks a step forward because researchers have now created the protein (and analyzed it) in a laboratory setting — bringing it a step closer to possible use for humans, researchers said.

The protein’s bacteria-fighting qualities could help humans stave off the ever-increasing and worrisome resistance to antibiotics that bacterial infections have been developing around the planet. It’s a problem the World Health Organization has identified as “one of the biggest threats to global health, food security, and development today.”

If nothing is done, “we are heading for a post-antibiotic era, in which common infections and minor injuries can once again kill,” according to the non-government organization.

And that’s where scientists say the platypus comes in.

When scientists looked at the protein’s structure, they found it had a “unique, never-before-seen fold.” The shape of the protein was similar to a ringlet, which is how the researchers settled on the name “Shirley Temple,” in honor of the curly-haired child star.

“It’s the shape of proteins which dictate their function,” Newman told the Guardian. “So the hope is that the novel structure, in the best possible world, would eventually lead to a therapeutic that is based on a completely different way of dealing with microbial infections than our current antibiotics.”

Why is the protein only present in platypus milk, and not in other mammals? Researchers think they have the answer to that, too.

Another anatomical anomaly platypuses boast is that, unlike most mammals, they don’t have nipples. Instead, young platypuses feed off milk that mother platypuses secrete onto their bellies, researchers said. In essence, the mothers are sweating milk.

But that method of feeding young leaves the milk susceptible to contamination by dangerous environmental bacterias, researchers said.

That’s where the platypuses’ unique antibacterial protein comes in, researchers suggest, to protect the mother’s milk and their offspring from bacterial infiltration. (Teats, meanwhile, are a relatively sterile way for milk to move from mother to offspring, the Guardian reports.)