Mucous cells on the stomach lining

Bacteria biofilms, when formed, pose a significant health risk in industrial applications, like food processing, and medical settings. Researchers at MIT suggest a new weapon for fighting bacterial formations in the form of nature’s own line of defense – mucus.

Mucus lines most of the wet surfaces of the body, including the respiratory and digestive tracts, and acts as a barrier against infection. However, scientists did not know until recently how exactly does it manages this.

“Mucus is a material that has developed over millions of years of evolution to manage our interactions with the microbial world. I’m sure we can find inspiration from it for new strategies to help prevent infections and bacterial colonization,” says Katharina Ribbeck, the Eugene Bell Career Development Assistant Professor of Biological Engineering and senior author of the paper

Ribbeck and her colleagues found that mucus contains proteins that prevents bacteria from adhering to surfaces, like tissue. These findings were made after the scientists studied the behavior of Pseudomonas aeruginosa bacteria in a growth medium that contained soluble purified mucins — long proteins with many sugar molecules attached.

For the bacteria to effectively penetrate the mucus layer and reach tissue where it can wreak havoc, it needs to bind and form bacterial clusters. Clumps of bacteria are much more difficult for the immune system to clear, because immune cells are specialized to attack individual bacterial cells.

“In general, you want to have bacteria around, you just don’t want them to team up,” Ribbeck says. “You want to them to be mixed with many other bacteria that are good for you. You don’t want a single species to take over, because then they may overgrow the system.”

The mucus was found to stop bacteria from adhering and thus prevent cluster formations, instead it leaves individual bacteria suspended in a gooey mix. What important is that mucus does not kill bacteria, but simply blocks it from reach its target. This ensures that bacteria is less likely to develop tolerance to mucins, as they do under antibiotics that kill them.

In aging, dehydrated or diseased bodies, mucus formation doesn’t regenerate as well as it should, and thus bacteria clusters sometimes manage to form, causing infections in the process.

The researchers are now investigating exactly how mucins prevent bacteria from losing their motility, and also how they block infection by nonmotile bacteria. Still, their study proves that mucus isn’t a simple slimy substances that blocks just about anything. The researchers plan on developing mucin coatings that may help prevent biofilm formation on medical devices and that could also find applications in personal hygiene: incorporating them into products such as toothpaste or mouthwash may supplement the body’s own defenses, especially in people whose natural mucus has been depleted, Ribbeck says.

Findings appear in the journal Current Biology.

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