Scientists in Denmark got bacteria to do something surprising—they made milk proteins, without any cows or milk.
This breakthrough, led by researchers at the Technical University of Denmark and Chalmers University of Technology in Sweden, may upend how we think about dairy. The team has figured out how to coax humble E. coli into producing a crucial milk protein known as αs1-casein, with the same structure and behavior as the version found in cow’s milk.
Their secret? Teaching bacteria a molecular trick that even cutting-edge dairy-free startups have struggled with for years.
The Molecule That Makes Cheese Possible
Caseins are the proteins that allow milk to be… well, milk. They clump into microscopic globules called micelles that carry calcium, give cheese its stretch, and help yogurt stay creamy. But mammalian cells modify casein proteins after producing them. One especially vital tweak, called phosphorylation, involves adding phosphate groups that allow the protein to bind calcium and form stable micelles.
Without this modification, caseins are nutritionally and functionally incomplete.
This has been the stumbling block for cellular agriculture companies hoping to use microbes to make milk. “This has been tried for a long time now,” said Suvasini Balasubramanian, the study’s lead author, in an interview with New Scientist. “All the start-ups and companies have been struggling.”
The researchers’ new study, published in Trends in Biotechnology, offers two workarounds. One involves engineering bacteria to add the phosphates themselves. The other fakes the modification entirely, with a little molecular sleight of hand.
Milk Without Mammals
To get around a key hurdle, the researchers tried two different ways to make milk protein in bacteria.
In the first approach, they gave E. coli bacteria extra instructions, adding three enzymes borrowed from a common soil bacterium. These enzymes helped the bacteria stick phosphate groups onto the casein protein as it was being made. That detail matters: the phosphate groups help the protein behave like the one found in real milk.
In tests, this method worked. The lab-grown casein ended up with phosphate groups in the same places as the version from cows.
The second method skipped the phosphate step. Instead, the scientists tweaked the casein’s building blocks. They swapped in a different ingredient (an amino acid called aspartic acid) that acts a bit like phosphate. This created a “phosphomimetic” version of casein that imitates the effects of the real thing.
Both lab-made versions of casein—one with added phosphates and one with the chemical mimic—were tested. The results showed that they could bind calcium well and were easy to digest, just like the natural protein in dairy.
The Cheese Test Comes Next
Caseins are the backbone of cheese. Without them, making plant-based cheese that melts, stretches, or tastes right has been a nearly impossible task.
Now that researchers can make functional caseins from microbes, they’re preparing for the next step: trying to make cheese.
“It might work,” Balasubramanian said. “Or it might turn out other types of casein are needed too.” In particular, she pointed to κ-casein, another variant involved in stabilizing casein micelles and modified not by phosphate, but by sugar molecules.
The researchers are currently scaling up their process using bioreactors and testing different feedstocks, including sugars derived from alfalfa grass.
A Greener Future for Dairy?
Producing a kilogram of cheese the conventional way emits around 24 kilograms of carbon dioxide. That’s more than 10 times the footprint of most plant-based foods. But lab-grown dairy proteins could drastically cut emissions, especially if the bacteria are fed with low-carbon sources and powered by renewable energy.
“It will significantly reduce the carbon footprint,” Balasubramanian said.
The global casein market, valued at $2.7 billion in 2023, is projected to nearly double by 2033. Meeting that demand without more cows, more methane, and more land use is becoming an environmental imperative.
Still, many questions remain. Can these caseins form micelles in real food systems? Will they behave the same way in cheese-making vats as they do in test tubes? And will people accept dairy products that never came from an udder?
The research is currently at technology readiness level 4—a point in development where proof of concept has been achieved, but real-world products are still a few years away.
Yet the trajectory is clear. Animal-free dairy is no longer just a dream. It’s fermenting quietly in a flask somewhere in Denmark, molecule by molecule.
Now, it’s up to food scientists—and perhaps a few adventurous cheesemakers—to turn that breakthrough into brie.
