FDAAs showed what was happening at each stage and gave the team a ‘eureka moment’ when they saw that the predatory bacteria make a ‘porthole’ with a central pore surrounded by a reinforcing ring containing D amino-acids. Bdellovibrio squeeze through this pore and fill it in with more D-amino-acid containing material so the invaded bacteria don’t burst and all their internal cell contents can be privately eaten by the predators without leaking away to the outside.

As this is happening the predatory bacteria go on to add more FDAAs in all around the wall of the invaded bacterium, not just at the porthole ring. In the experimental conditions the predatory bacteria ‘painted’ this coloured FDAA, rather like a molecular scale ‘fresco’, to the walls of the invaded bacterium in a process which reinforces the wall of invaded bacterium so it doesn’t collapse before the predator has eaten the nutritional contents inside. Dr Carey Lambert from Nottingham joined the project and was able to find some of the ‘tools’ that apply the frescos—these are a group of enzymes that have been little studied until recently.

Professor Sockett concludes: “It is remarkable to see this in action at such a tiny scale and also useful. Knowing more about the mechanisms used by the invading predatory bacteria could help design new ways of killing pathogens.  Now that the invasion processes have been defined it should be possible to gather all the tools needed to invade and consume pathogenic bacteria without releasing large amounts of their pathogenic cell materials by them bursting.”

The project was funded by grants and fellowships to the researchers from the Leverhulme Trust, the BBSRC, EMBO, The Wellcome Trust and National Institutes of Health.

It is a truly multinational effort with Turkish, English and American scientists working with help from French and German colleagues to understand processes that could help in the development of future effective antibiotics on a truly tiny molecular scale.