Biofilm Formation As a Response to Ecological Competition
Fig 2
Round-robin tournament among natural isolates of P. aeruginosa showing strong competitive effects upon strain mixing.
Five isolates were mixed together in all pairwise combinations and data from each mixture are shown in a corresponding panel. A) Example data from strains 4 and 1 illustrating the different measures in a given mixture. In this example, mixing the two strains increases biofilm, decreases planktonic cells, and strain 1 (yfp-labeled) strain strongly outcompetes strain 4 (cfp-labeled) strain. B) All data from the round-robin tournament. As in panel A, the backdrop to each panel is an epifluorescence image of the coculture biofilm from a coverslip. All other data shown are from 96-well microtiter experiments. Specifically, the left-hand side graph in each panel shows information about the biofilm. Here, the plotted points show biofilm formation in the crystal violet assay by the cfp-labeled strain alone, both strains together, and the yfp-labeled strain alone, from left to right. The pie chart on the left shows frequencies of the two strains in the biofilm. The right-hand side of each panel—graph and pie chart—shows the planktonic cell data from the same experiments as the biofilms measurements. cfp and yfp stand for cyan and yellow fluorescent protein, respectively. Plotted data show means and 95% confidence intervals. Find numerical values in S1 Data.