Kind Discrimination and Competitive Exclusion Mediated by Contact-Dependent Growth Inhibition Systems Shape Biofilm Community Structure
Figure 9
CDI system-mediated kind discrimination during polymicrobial biofilm formation of Bt-Bp1106a-1 and Bt-Bp1106a-2 bacteria.
Confocal microscopy and quantitative analysis of polymicrobial biofilms 72∶1 starting ratio with the following strains: I. Bt-Bp1106a-1 and Bt-Bp1106a-2, II. Bt-Bp1106a-1 and Bt-Bp1106a-2::bcpIBp1106a-1, III. Bt-Bp1106a-1 and Bt-Bp1106a-2::bcpIBtE264, and IV. Bt-Bp1106a-1::bcpIBp1106a-2 and Bt-Bp1106a-2::bcpIBp1106a-1. For A) and B), strains in red carry a constitutive rfp gene, strains in green carry a constitutive gfp gene. For COMSTAT analysis in C) and D), green bars correspond to gfp expressing strain. Bars represent the mean of at least three independent experiments and error bars indicate the SEM. Significance was determined by two-tailed t-tests; *** p<0.0006; ns, not significant, comparing each strain to Bt-Bp1106a-2 (roman numeral I). A) Images taken of the plane at the bottom of the biofilm (substratum). Scale bar = 10 µm. B) Fluorescent and DIC merged images taken in a plane of focus approximately half way between the top and bottom of the biofilms. Scale bar = 32 µm. C) COMSTAT analysis of a single plane at the bottom of the biofilm (substratum), as shown in A). D) COMSTAT analysis of the total biofilm (i.e., all planes), from experiments shown in B).