Around the turn of the century, microbiologists at Danisco USA Inc. had a problem: The bacteria they used to make yogurt and cheese were getting infected with viruses. Investigating more deeply, the scientists found that some bacteria possessed a defense system to fight off such viral invaders. These virus-resistant bacteria carried weird, repetitive collections of DNA letters in their chromosomes — bits of DNA from their encounters with past viruses that the microbes had “saved” in their own genomes. It was a form of molecular memory akin to the way that our own immune system remembers invaders so it can make antibodies against a recurring infection.
In this case, the microbes’ immune system, dubbed CRISPR-Cas, or more casually, just CRISPR, shreds any viral genome that matches the sequences in their molecular memory banks. The yogurt-makers weren’t looking for biotechnology’s Next Big Tool. They just wanted to preserve the products in ...
