Figure 1. Matrix non-producer strain does not incorporate into the wild-type pellicle.

(a) Pellicle biofilms of wild-type (WT) Bacillus subtilis 168 and its mutant derivatives were recorded using an Axio Zoom microscope equipped with a black and white camera. Scale bar, 1 cm. The reflection of the light source can be observed in the ΔtasA culture. (b) Pellicle competition assay between Δeps–ΔtasA and WT (n=25). (c) Confocal microscopy images of pellicle biofilm from culture initially consisting of a 1:1 ratio of WT and Δeps–ΔtasA (upper) and cells with swapped fluorescence protein labels (lower). Scale bars, 10 μm. (d) Planktonic culture competition assay between Δeps–ΔtasA and WT (n=25). Boxes represent Q1–Q3, lines represent the median, and bars span from max to min. The experiments were independently repeated at least three times. * indicates that the relative c.f.u. is significantly higher than the relative c.f.u. of Δeps–ΔtasA ancestor in the pellicle (in panel b).