Yeasts may let us cut cows out of the process of making milk
Milk is a substance that has, for millions of years, been made exclusively by mammals. Most species use the mix of water, proteins, minerals and sugar to feed their babies exclusively, but humans have have decided that it’s worth consuming dairy throughout our lives, even if we get it from other animals like cows and goats. With demand growing for dairy, but livestock requiring a lot of resources and space to raise, new sources of milk are being developed, even from well outside the animal kingdom.
The newest form of milk should look a lot like what we’re used to getting from cows, but it will largely be sourced from yeasts. This isn’t to say that we’ll be directly milking yeasts, but that the yeasts will grow many of the crucial proteins, like casein, normally produced by cows. Researchers were able to isolate which genes are responsible for these proteins in the cows, and then inserted those genes into the yeast’s relatively simple genome.
With yeast producing these proteins, many of the other ingredients in bovine milk can also be sourced without actual cows. There are some things beyond the reach of yeast though, such as sugars like lactose (or some equivalent) and immunoglobins that help protect against bacteria like E. coli and Helicobacter pylori.
Alternatives to animals
Yeast-sourced milk isn’t the first cowless milk option, but it’s the closest you’ll find to the real thing. Soy and rice milks have been fairly decent analogs to bovine milk for a while, but yeast will offer something much closer to a mammalian food-source without involving too many large, resource-heavy mammals (unless you count the humans involved…) It will be a while before it can compete with the price of milk from cows, but as people become more sensitive to how much it costs the world to raise even a single cow, this might seem like a very efficient option.
Source: Your Breakfast Is About to Take a Weird Turn by Marta Zaraska, Mother Jones