Scientists have found a new way to make milk proteins without using cows. This could help provide tasty and healthy dairy foods while being much better for the planet. The new method uses bacteria to create αs1-casein, a key protein in milk, that is just as functional as what’s found in cow’s milk.
Why Milk Proteins Matter
Milk proteins are important for nutrition, they help give foods like cheese and yogurt their flavor, texture, and health benefits. The main proteins are split into two groups: caseins and whey proteins. Caseins are especially useful because they help make foods creamy and stable. They’re also used in sports nutrition and medicines.
The market for milk caseins is growing fast, but making them the traditional way, i.e. by milking cows, uses a lot of land and water and creates greenhouse gases. That’s why scientists are searching for animal-free ways to make these proteins.
The Challenge: Making Functional Caseins Without Cows
Some companies can already make whey proteins with microbes through special fermentation, but caseins are tougher to make. That’s because to work properly in foods, caseins need to be phosphorylated. This means they must have tiny phosphate molecules attached in exactly the right places. This process helps caseins bind with calcium, which is vital for forming the small clumps (micelles) that give cheese and other dairy foods their special texture.
Bacteria like E. coli are useful for producing proteins, but they don’t naturally add these phosphate groups like cow cells do. This is a big problem for scientists who want to make cow-like caseins in the lab.
The Breakthrough: Bacteria That Can Phosphorylate Milk Proteins
Researchers solved this by engineering E. coli to produce bacterial enzymes called kinases. These kinases can add phosphate groups to the casein at the precise spots needed. The team used kinases from a type of bacteria called Bacillus subtilis (specifically, PrkD and YabT). First, they checked if these kinases could modify the milk protein in test tubes. They found that they could attach phosphates in all the right places, just like in cow milk.
The team also tried an alternative method, called phosphomimetic substitution, where they swapped out certain parts of the protein to mimic phosphorylation without needing kinases. Both strategies worked: the caseins made by the bacteria were able to bind calcium and form structures similar to natural casein micelles in cow’s milk.
What Does This Mean for the Future?
Both the phosphorylated and phosphomimetic caseins performed much like normal milk proteins. This means scientists can now make important milk proteins without cows, using just bacteria in the lab. These animal-free caseins could be used for making cheese, yogurt, and other products all while reducing the environmental impact of dairy farming.
Although the current work is still at a laboratory scale, it marks a big step toward sustainable, animal-free dairy. If scaled up, this technology could change the way we make food, delivering the taste and nutrition of milk without relying on animals or large farms.
