A dynamic model for diauxic growth, overflow metabolism, and AI-2-mediated cell-cell communication of Salmonella Typhimurium based on systems biology concepts.

The last decades, the research on bacterial cell-cell communication or quorum sensing has been quite intense. Quorum sensing allows bacteria to coordinate their behavior and to act as one entity. Quorum sensing controls microbiological functions of medical, agricultural and industrial importance and a better understanding of the underlying mechanisms and the conditions under which the signaling occurs, offers possibilities for new applications. In this article a dynamic model for diauxic growth, overflow metabolism and AI-2-mediated cell-cell communication of Salmonella Typhimurium is presented. The growth, and the production and uptake of the AI-2 signaling molecule of S. Typhimurium are investigated in a controlled environment (bioreactor). In a first stage a model is developed to describe diauxic growth and overflow metabolism. This model is extended in a second stage to describe AI-2 dynamics of S. Typhimurium in relation to the growth kinetics and biomass concentration. It is illustrated how this model can be employed to test hypotheses concerning AI-2 dynamics on the basis of macroscopic data.