DEEP in your lungs, there’s a battle raging. It’s a warm, moist environment where the ever-opportunistic bacterium Pseudomonas aeruginosa has taken up residence. If your lungs are healthy, chances are the invader will be quickly dispatched. But in the mucus-clogged lungs of people with cystic fibrosis, the bacterium finds an ideal habitat. First, the microbes quietly multiply and then they suddenly switch their behaviour. A host of biochemical changes sticks the population of cells together, forming a gluey biofilm that even a potent cocktail of antibiotics struggles to shift.
Microbes like P. aeruginosa were once thought of as disorganised renegades, each cell working alone. Microbiologists like Thomas Bjarnsholt, who is battling to understand how P. aeruginosa causes chronic infection in people with cystic fibrosis, now know otherwise. They are up against a highly organised army, using a sophisticated communication system to coordinate its behaviour.
But it’s Bjarnsholt’s latest discovery that reveals microbes’ gift for language: the bacteria aren’t just talking amongst themselves, but also quietly listening in on signals sent by their human host. So when a cavalry of white blood cells arrives to repel the invading bacteria, the entrenched biofilm senses their presence, and launches a coordinated counterattack (Microbiology, vol 155, p 3500). The microbes release deadly compounds called rhamnolipids, which burst the white blood cells, killing them before they can even take aim, says Bjarnsholt, who is at the University of Copenhagen in Denmark.
Examples like this belie the notion that bacteria are simple, silent loners. Over recent decades, many species of bacteria have been shown to be in constant communication with each other. But now an ...