Microbiome study finds bacteria in human gut rarely update their CRISPR defense systems
Originally published by Anne Trafton, Massachusetts Institute of Technology, on December 23, 2024
A study from MIT biological engineers has yielded new insight into how bacteria in the gut microbiome adapt their CRISPR defenses as they encounter new threats. Credit: Donny Bliss, NIH
Within the human digestive tract are trillions of bacteria from thousands of different species. These bacteria form communities that help digest food, fend off harmful microbes, and play many other roles in maintaining human health.
These bacteria can be vulnerable to infection from viruses called bacteriophages. One of bacterial cells' most well-known defenses against these viruses is the CRISPR system, which evolved in bacteria to help them recognize and chop up viral DNA.
A study from MIT biological engineers has yielded new insight into how bacteria in the gut microbiome adapt their CRISPR defenses as they encounter new threats. The researchers found that while bacteria grown in the lab can incorporate new viral recognition sequences as quickly as once a day, bacteria living in human gut add new sequences at a much slower rate—on average, one every three years.
The findings suggest that the environment within the digestive tract offers many fewer opportunities for bacteria and bacteriophages to interact than in the lab, so bacteria don't need to update their CRISPR defenses very often. It also raises the question of whether bacteria have more important defense systems than CRISPR.
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