Glycans found in mucus can stop bacteria communicating, developing resistance and forming infectious biofilms.

We produce 1.5 litres of mucus per day and it lines over 200 square metres of our bodies, including the digestive tract, lungs and urinary tract. However, new research has revealed that the mucus is a lot more than just a protective barrier to infection. The mucus is full of branched sugar molecules, known as glycans, that appear to be responsible for its strong anti-microbial activity.

The study focused on how glycans can regulate the behaviour of the opportunistic pathogenic bacteria Pseudomonas aeruginosa. Glycans bind to the mucin molecules, the proteins that give mucus its gel like consistency, to form a ‘bottlebrush-like’ structure. The researchers isolated glycans from mucus and exposed them to the bacteria.

Upon glycan exposure, the bacteria were no longer able to exhibit a lot of harmful behaviour. They could not produce toxins, attach to host cells or express genes necessary for bacterial communication. The bacteria could not form biofilms, connected networks of bacteria that adhere tightly to body surfaces, making the infection difficult to treat.

The glycans also prevented the bacteria from engaging in horizontal gene transfer, used to transfer antibiotic resistance genes to each other so the whole bacterial population can become resistant.

The researchers will now study the effect of individual glycan molecules on bacteria, to understand the molecular mechanisms behind their anti-microbial activity. It is possible that glycans can initiate genetic changes in the bacteria to prevent then from expressing harmful phenotypes.

Glycans could therefore be developed into new anti-bacterial treatments.