World Science asked leading microbiologist Stephen P. Diggle to comment on a study on “backstabbing bacteria” reported in World Science and presented Sept. 6 at the fall meeting of the Society for General Microbiology in Nottingham, U.K. Diggle, a Royal Society university research fellow at Nottingham University, is one of the scientists involved in the study and is the professor of its lead researcher, Ph.D. student Eric Pollitt.
WS: Could you concisely describe how bacterial cells interact socially with each other and how an understanding of this can help us to further understand infectious disease?
D. : In the last 20 years, we have started to appreciate that bacteria are highly interactive and exhibit a number of social behaviours. One key phenomenon found in many species of bacteria is “Quorum Sensing” or QS, which describes the accumulation of signal molecules produced by bacterial cells [and released into] the surrounding environment. By sensing when the signal is at a critical concentration, bacterial cells are able to work together to coordinate production of damaging toxins and this helps the infection to overwhelm the host. Microbiologists have made huge strides in gaining an understanding of the genetic mechanisms involved in such behaviours, but more recently we have been interested in a more Darwinian approach - how do these behaviours evolve and how are they maintained in nature?
WS: Besides the interest that it has in its own right, would you say that this research could prove useful from the medical perspective?
D.: Yes indeed. A number of microbial social behaviours are involved in bacterial virulence, and we hope to put the bacteria themselves at work as our allies in stalling or preventing infections. These behaviours are costly for bacterial cells to perform and are therefore subject to exploitation by non-cooperating “cheats” who gain all the benefits from the cooperation of others but pay none of the costs. Crucially, when a behaviour is related to virulence, a cheat is often less virulent and this has benefits to an infection when they spread through it. It's rather analogous to a human society when people don't pay their taxes. These people still benefit from taxes paid by others but to an overall detriment to the population as a whole.