Samenvatting

Accumulating evidence dismisses the idea that bacteria are solitary bugs, living a completely independent existence. Instead, this definition is being replaced by the notion that bacteria are intimately communicating organisms holding tight relations to one another. One such process through which this is achieved is called quorum sensing, a cell-density-dependent way of controlling gene expression in communities of single- and mixed cell populations. This discovery and the on-going investigations towards this phenomenon also reveal appealing alternatives to microbial control and culturing of novel microorganisms. This review aims to elucidate the mechanisms underlying this process of quorum sensing and its implications on present-day knowledge on microbial cell-cell signalling. Here, several model organisms are displayed with their cognate signalling systems, such as the LuxI/LuxR system in Vibrio fisheri, Agr system in Staphylococcus aureus and AI-2 system in Vibrio harveyi. In general, bacterial communication is achieved by secreting small, signalling molecules or by actively transporting peptide signals into the environment. This signal is received by all bacteria which share the cognate receptor to that signal. Quorum sensing controls many natural processes such as virulence, bioluminescence and biofilm formation, making this process an important area of investigation due to its impact on different fields.