For some scientists, there is no place more romantic than a cheese cave. When Tufts University biologist Benjamin Wolf, then a biology postdoc, took his colleague Rachel on a surprise date with her boyfriend in a Vermont cheese cave, a marriage proposal ensued. And according to a new study by Wolfe and his colleagues, paper V Current biologythe same thing happened with the discovery in the field of evolution.
Some cheeses are ripened in caves, where they attract microbes—yeasts, bacteria, and fungi (molds)—that form a crust on the surface of the cheese. Shape type Penicillium (the same genus that produces the human antibiotic, but of a different species) speeds up the ripening of cheese. P. Roquefortfor example, launches blue cheese, and P. white Gives a soft creamy texture.
Some molds are beneficial, while others can spoil the cheese, so aging cheeses is a delicate balance between growing and removing mold.
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Wolfe was intrigued by the marriage proposal scene in a Vermont cheese cave, and he took samples of Bailey Hazen's blue cheese back to his laboratory and froze them for several years. At that time, he noticed a mottled greenish-brown microbial rind on the cheese, which he analyzed, realizing that it consisted primarily of a filamentous fungus. Regular brush.
But when he sent his graduate student Nicholas Lowe to collect more samples from the farm a few years later, the cheese rinds were completely white.
“It was really interesting because we thought this might be an example of evolution happening right before our eyes,” said Wolfe, now a microbiologist at Tufts University. V statement. The cheese-making process did not change, nor did the environment in the caves, suggesting that the microbes evolved independently in response to some invisible selection pressure.
When Lowe, Wolfe and colleagues analyzed the new composition of microbes in the cheese rind, they discovered a genetic explanation for the color change. Gene disruption alb1which plays a role in melanin production, changed the skin from greenish-brown to white. The researchers suggest that in the darkness of the cave, melanin was no longer needed to protect against sunlight. So, in an example of “relaxed selection,” the melanin production pathway was genetically suppressed.
“By disrupting this pathway and going from green to white, mushrooms are essentially saving energy to invest in other things for survival and growth,” Wolfe added.
Watching mold evolve may not spark new romances, but it will likely influence the cheese-making process through targeted cultivation and selection of microbial communities that can impart new flavors to cheese.
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