Monitoring Intraspecies Competition in a Bacterial Cell Population by Cocultivation of Fluorescently Labelled Strains

This method uses co cultivation of fluorescently labeled bacillus sutilis to monitor the rapid clonal expansion and elimination of beneficial and detrimental mutations in a bacterial cell population over time. First, prepare the pre cultures of the bacteria for the competition experiment. Mix equal amounts of the fluorescently labeled strains and co cultivate the bacteria under different nutritional conditions.

Then collect the samples at different time points, dilute appropriately and propagate the cells on agar plates. Now visualize and count the surviving strains by stereo fluorescence microscopy. Ultimately, results can determine the percentage of the surviving bacteria with respect to the whole number of counted colonies.