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Bacterial cooperation at the molecular level

An infection with a bacterium that grows in a biofilm can be bad news. Biofilm bacteria are often associated with antibiotic resistance and they cause chronic infections.
Bacterial cooperation at the molecular level
A biofilm is a community of microbes attached to a surface. As such, they are wrapped up in a polymer framework that facilitates adhesion and the development of 3D ordered structures. Perhaps the most worrying property is an antimicrobial barrier.

The EU-funded PSL (Intercellular signalling functions of bacterial biofilm extracellular matrix) project has investigated and compared the social value of the two common polysaccharides PSL and PEL in Pseudomonas aeruginosa. An opportunistic pathogen, P. aeruginosa can cause sepsis and ventilator-associated pneumonia.

PSL are shared goods that benefit all and even non-producers can gain advantage of say, protection against antibiotics, whereas PEL are private goods and their mutants are rapidly outcompeted by PEL producers. PEL on the other hand does not confer common protection against antimicrobials.

After analyses of metallic molecules such as silver and gallium, the researchers concluded that these new generation anti-biofilm therapeutic drugs are promising but need further study.

Another avenue of possible action against biofilms is the Type IV pilus used for surface motility. Possibly important for post-adhesion organisation, they are not PSL receptors for signalling but there appear to be links between PSL and Type IV that help surface motility.

The researchers also looked at links between regulation of PEL and PSL polysaccharides. Previous research suggested that the global posttranscriptional regulator, RsmA may have a hand in regulating both polysaccharides. However, PSL project research indicates there are two intermediate regulators between PEL and RsmA indicating no direct relationship between the two.

The project has constructed a substantial knowledge platform on a topic that has substantial significance in the battle against antimicrobial resistance. Non-selective ways of killing bacteria normally increase the selective pressure for resistance. Targeting the molecular basis of biofilm production removes this tendency and is likely to provide a more sustainable solution for bacterial infection.

Related information


Biofilm, antibiotic resistance, chronic infection, PSL, PEL, RsmA
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