Why Cheese Mold is Rapidly Evolving—And What That Means For Cheese Lovers

Cheese mold is a bit like Spiderman: it adopts DNA from other species and gains new powers. The mold uses the new, adopted genes to better survive in a milk-based environment. That might sound less exciting than Peter Parker's story, but according to scientists, it’s a sign that cheese mold is in evolutionary overdrive—and it looks like humans are responsible. 

According to the New York Times, humans have been using different kinds of mold to make cheese for thousands of years. But it wasn’t until the 20th century that cheese makers actually started to learn the science behind their craft, identifying the different species of mold that help create different varieties of cheese. That breakthrough allowed cheese makers to industrialize production, making cheese on a larger scale than ever before. 

Now, evolutionary biologist Rodríguez de la Vega and his colleagues have discovered that mass production of cheese has had a massive impact on the types of mold used to make it. In a recent study that appeared in the journal Current Biology, the scientists reported that they sequenced the genomes of ten species of Penicillium, the type of mold used to make cheese. (It’s important to note that though Penicillium is used in cheese production, wild species of Penicillium usually feed on decaying plant matter, not milk.) Out of the ten types of Penicillium examined in the study, scientists chose six that grew on milk—either because they’re used in cheese production, or contaminate cheese—while the others were never found in cheese at all. 

As the scientists studied the mold genomes, they started to find large sequences of DNA that looked out of place. They realized that the cheese molds were swapping genes, borrowing DNA from distant Penicillium species, in a process called horizontal gene transfer. The new gene sequences helped the cheese molds thrive on cheese in different ways.

For example, a DNA sequence scientists have named “CheesyTer” helped molds break down lactose, the form of sugar found in milk. However, the gene also slowed down their ability to break down simple sugar, meaning the gene wouldn’t be particularly useful in the wild, but is extremely helpful for the molds used in cheese production.

These genetic mutations are fueled by the mass production of cheese, and their discovery has real implications for cheese makers. On the one hand, there is some concern that the rapid evolution of cheese molds may strengthen the types of mold that contaminate cheeses, making them more difficult to eradicate. On the other, Tatiana Giraud, who co-authored the cheese study, notes that understanding mold evolution could help cheese makers come up with ideas for new flavors.