Cooperation and conflict in quorum-sensing bacterial populations

Abstract

It has been suggested that bacterial cells communicate by releasing and sensing small diffusible signal molecules in a process commonly known as quorum sensing (QS). It is generally assumed that QS is used to coordinate cooperative behaviours at the population level. However, evolutionary theory predicts that individuals who communicate and cooperate can be exploited. Here we examine the social evolution of QS experimentally in the opportunistic pathogen Pseudomonas aeruginosa, and show that although QS can provide a benefit at the group level, exploitative individuals can avoid the cost of producing the QS signal or of performing the cooperative behaviour that is coordinated by QS, and can therefore spread. We also show that a solution to the problem of exploitation is kin selection, if interacting bacterial cells tend to be close relatives. These results show that the problem of exploitation, which has been the focus of considerable attention in animal communication, also arises in bacteria.

Bacteria electrical detection using 3D silicon nanowires based resistor

“…The high value reported of the average electrical resistivity of a single nanowire for undoped SiNWs is related to carriers trapping effect at defects located at interconnections between nanowires and induced by gold impurities at the surface of the nanowires. (for an average value R 0 ≈1.9×10 9 Ω), and validate the equivalent electrical model given by (1).…”

“…In addition, complex instrumentation [1] is required in most conventional methods, and cannot be used on site.…”

Bacterial cell‐to‐cell signaling promotes the evolution of resistance to parasitic bacteriophages

“…The QS‐signaling of lasI , rhlI , pqsA mutants was activated using 50 μmol/L final concentrations of 3O‐C 12 ‐HSL ( lasI ), C4‐HSL ( rhlI ), and PQS ( pqsA ) signal molecules (Diggle et al., 2007). Signal‐blind mutants were used as controls.…”

Bacterial competition and quorum‐sensing signalling shape the eco‐evolutionary outcomes of model in vitro phage therapy

“…In addition to P. aeruginosa (Diggle et al., 2007) , we used Staphylococcus aureus subsp. aureus (DSM‐20231) and Stenotrophomonas maltophilia (DSM‐50170) bacteria in our experiments.…”

“…We chose P. aeruginosa as our focal species as it is one of the most common causes of morbidity for patients with CF, while S. aureus and S. maltophilia often coexist with P. aeruginosa among Haemophilus influenza, Streptococcus pneumoniae, Burkholderia cenocepacia, Ralstonia and Achromobacter (Folkesson et al., 2012; Jelsbak et al., 2007). To compare the effect of pathogen genotype, two strains of P. aeruginosa were used: QS signalling PAO1 and QS‐deficient PAO1 lasR mutant strains (Diggle et al., 2007). Apart from the mutation in QS signalling pathway, the two isolates were otherwise isogenic (Fletcher et al., 2007).…”