Social interactions in bacterial cell-cell signaling.

Cooperation and conflict in microorganisms is being recognized as an important factor in the organization and function of microbial communities. Many of the cooperative behaviors described in bacteria are governed through a cell-cell signaling process generally termed quorum sensing. Communication and cooperation in diverse microorganisms exhibit predictable trends that behave according to social evolutionary theory, notably that public goods dilemmas produce selective pressures for divergence in social phenotypes including cheating. In this review, we relate the general features of quorum sensing and social adaptation in microorganisms to established evolutionary theory. We then describe physiological and molecular mechanisms that have been shown to stabilize cooperation in microbes, thereby preventing a tragedy of the commons. Continued study of the role of communication and cooperation in microbial ecology and evolution is important to clinical treatment of pathogens, as well as to our fundamental understanding of cooperative selection at all levels of life.