Microbial dinner-party conversations: the role of LuxS in interspecies communication

Bacteria have a tendency to be gregarious by nature. Whether on abiotic surfaces in the environment or on the mucosal surfaces of humans, bacteria accumulate in complex multi-species communities. In these dynamic accretions, bacteria can be densely packed and often depend on each other for the provision of metabolic substrates. Under these circumstances, it will be advantageous for bacteria to be able to detect the presence of their neighbours, to communicate with them and to co-ordinate various physiological activities. Such cell-cell sensing and communication systems can be established through the release and detection of chemical signalling molecules. While originally considered a feature characteristic of eukaryotes, the exchange of chemical signals has now been demonstrated in many bacterial species and ecosystems. Indeed, it has even been suggested that assemblages of bacterial species can be considered as proto-multicellular organisms, whereby biological processes are controlled for the benefit of the entire community. Regardless of the extent to which bacterial communication represents a step on the road to multicellularity, it is becoming increasingly apparent that the signalling systems devised by bacteria are essential for successful relationships with other bacteria and with eukaryotic hosts.