The experimental set up on one of Diamond's MX beamlines, I04
Biofilms are the predominant life form of bacteria. In this state, bacteria grow in organised coloniesand become immobile – this can make them really difficult to get rid of. Biofilms can cause chronic infections, such as non-healing wounds, and persistent infections that affect people with cystic fibrosis. They also represent health threats through growth on implants or catheters.
Jeremy Webb, the lead microbiologist from Southampton, explains: “Biofilms are extremely common, in fact they account for around 80% of all bacterial infections. But when antibiotics were developed, they were designed to target single cell bacteria. Biofilms represent an entirely different mode of bacterial growth, and they can be made up of complex and structured communities of bacteria. The biofilm state and the heterogeneity within biofilms mean that they can tolerate up to 1,000 times more antibiotics than a single-celled bacteria.”
However biofilms do have an Achilles heel. In order to aggregate – that is, transform from free-living single cells into a biofilm cluster – they have to use a biological mechanism to change state. Once they’re aggregated in a biofilm, the bacteria can still separate again; and the fact that this reverse mechanism exists means that we can exploit it. By triggering the dispersal mechanism, it’s possible to break up the biofilm, leaving the individual bacteria on their own, ready to be destroyed by antibiotics. And this mechanism exists within all bacteria, which means that, if we can harness it, dispersal offers an entirely new approach to combatting bacterial infections.
Using Diamond's life science beamlines, the team are studying the atomic structure of bacterial molecules involved in triggering biofilm dispersion. Not all biofilms are the same, and different triggers for dispersion are currently being investigated. In Southampton, the team have developed their own method of dispersing biofilms using a common gas: nitric-oxide. For humans, nitric-oxide is known as a signalling molecule in many physiological and pathological processes, but for bacteria, it’s a signal to break up biofilms.