*Pseudomonas aeruginosa* is a bacterium that is commonly found in the soil and water. It is also an opportunistic pathogen, meaning that it can cause infections in people with weakened immune systems. In fact, *P. aeruginosa* is a leading cause of chronic lung infections in people with cystic fibrosis and bronchiectasis.
The bacterium is able to survive in oxygen-poor environments by producing a molecule called pyocyanin. Pyocyanin is a blue-green pigment that is toxic to other bacteria, but it also helps *P. aeruginosa* to survive by scavenging for oxygen.
Previous studies have shown that pyocyanin production is essential for *P. aeruginosa* to cause infections in mice. However, the exact mechanism by which pyocyanin helps the bacterium to survive in oxygen-poor environments has been unknown.
In the current study, the UEA researchers used a combination of genetic and biochemical techniques to identify the mechanism by which pyocyanin helps *P. aeruginosa* to survive in oxygen-poor environments. They found that pyocyanin binds to a protein called C55 in the bacterium's cell membrane. This binding event triggers a signal transduction pathway that leads to the activation of a number of genes that are involved in oxygen metabolism.
The researchers also found that pyocyanin helps *P. aeruginosa* to form biofilms. Biofilms are communities of bacteria that are attached to a surface. Biofilms are often found in chronic lung infections. The researchers found that pyocyanin helps *P. aeruginosa* to form biofilms by increasing the production of a molecule called rhamnolipids. Rhamnolipids are surfactants that help bacteria to adhere to surfaces.
The discovery of the mechanism by which *P. aeruginosa* survives in oxygen-poor environments could lead to new treatments for chronic lung infections such as cystic fibrosis and bronchiectasis. For example, it may be possible to develop drugs that inhibit the binding of pyocyanin to C55. Such drugs could prevent *P. aeruginosa* from surviving in oxygen-poor environments and could therefore help to clear chronic lung infections.
The study was published in the journal *Molecular Microbiology*.
