Luminescence control in the marine bacterium Vibrio fischeri: An analysis of the dynamics of lux regulation

A mathematical model has been developed based on the fundamental properties of the control system formed by the lux genes and their products in Vibrio fischeri. The model Clearly demonstrates how the components of this system work together to create two, stable metabolic states corresponding to the expression of the luminescent and non-luminescent phenotypes. It is demonst rated how the cell can "switch" between these steady states due to changes in parameters describing metabolic processes and the extracellular concentr ation of the signal molecule N-3-oxohexanoyl-L-homoserine lactone. Ln addit ion, it is shown how these parameters influence how sensitive the switch me chanism is to cellular LuxR and N-3-oxohexanoyl-L-homoserine lactone and co mplex concentration. While these properties could lead to the collective ph enomenon known as quorum sensing, the model also predicts that under certai n metabolic circumstances, basal expression of the lux genes could cause a cell to luminesce in the absence of extracellular signal molecule. Finally, the model developed in this study provides a basis for analysing the impac t of other levels of control upon lux regulation. (C) 2000 Academic Press.