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Bacteria make molecular snorkels for surviving in crowded spaces: antibiotics that fight enemies also provide access to oxygen.

SAN FRANCISCO -- Antibiotics made by Pseudomonas aeruginosa bacteria can serve as molecular snorkels, helping the bacteria breathe even if buried in mucus or squeezed into the middle of a colony.

The finding, reported by MIT researchers tars Dietrich and Dianne Newman December 16 at a meeting of the American Society for Cell Biology, reveals a new role for antibiotics produced by bacteria. Scientists previously believed that those antibiotics were mainly employed to fend off other bacteria.

P. aeruginosa is a pathogenic bacteria species that is harmless to most healthy people. But for people with cystic fibrosis--a genetic disorder that leads to a buildup of thick, stickymucus that clogs the lungs and digestive tract--the bacterium is deadly. P. aeruginosa invades the mucus, turning it blue-green with antibiotic pigments called phenazines and even destroying lung tissue,


The new study reveals that the molecules also help P. aeruginosa breathe and can act as communication signals that help shape how communities of the organism grow. Drugs that disrupt the multitasking molecules might provide new treatments for cystic fibrosis, the team suggests.

Oxygen is a scarce commodity in the mucus-clogged lungs of people with cystic fibrosis. Bacteria growing at a colony's outer edges may have access to oxygen, but bacteria buried under their siblings would suffocate without a way to gain oxygen. Phenazines act like molecular snorkels, giving bacteria that are crowded or submerged in mucus access to fresh air, Dietrich says.

Colonies of P. aeruginosa that make phenazines grow in petri dishes as smooth, shiny colonies. But bacteria that lack the molecules form wrinkled colonies. Dietrich thinks the wrinkles probably increase surface area to bring more bacteria in contact with oxygen.

The idea that bacteria can use phenazines to access essential nutrients, such as oxygen, is exciting, says Linda Thomashow, a research geneticist with the U.S. Department of Agriculture's Agricultural Research Service in Pullman, Wash. The result fits with her research, which shows that phenazines give bacteria a competitive advantage in soil.

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Title Annotation:Body & Brain
Author:Saey, Tina Hesman
Publication:Science News
Geographic Code:1USA
Date:Jan 17, 2009
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