Characterizing Quorum Sensing-Induced Bioluminescence in Variable Volumes With Vibrio fischeri Using Computer Processing Methods

Bacteria use the mechanism of quorum sensing to gather information about the density of other cells in their surroundings. Quorum sensing, in which bacteria sense chemical signals that increase in concentration as a function of surrounding cell density, leads to downstream changes in bacterial gene expression. These changes may include the activation of virulence or bioluminescence. In this study, we used Vibrio fischeri as a model to study the activation of bioluminescence by quorum sensing. We inoculated the same number of bacterial cells in 3 different culture volumes (1mL or small volume, 3mL or medium volume, and 5mL or large volume) and measured luminescence of the cultures over time. Using digital image processing to determine changes in luminescence over time, we found that cultures in smaller volumes reached peak illumination densities in less time than those in larger volumes. These results suggest that V. fischeri luminesce in response to cell density information in the environment and that we can use computer processing methods to study quorum sensing-induced bioluminescence. Studying the mechanisms by which bacteria use quorum sensing to activate gene expression may facilitate the development of therapies to inhibit bacterial virulence in the context of infectious disease.