Fig. 1.

eDNA is a major component of PA14 biofilm streamers. (A) Schematic of a biofilm streamer formed around a pillar, due to the combined action of the main flow (gray arrows) and the secondary flow (color scale). The x (gray arrows) and the z component (color scale) of the flow velocity around a 50-µm pillar were numerically computed (COMSOL Multiphysics) for a mean flow velocity of 500 µm/s. (B–D) Representative phase-contrast and fluorescence images of a portion of the biofilm streamers formed by P. aeruginosa PA14 WT cells attached to a 50-µm pillar within a microfluidic channel after 20 h of continuous flow of a dilute bacterial suspension at U = 2 mm/s. (E) Magnified view of C. The white arrow indicates corresponding points in the figures. Images were taken at channel middepth. Bacterial cells were imaged in phase contrast (B), eDNA was stained using red-fluorescent PI (2 μg/mL; B, C, and E) and Pel was stained using green-fluorescent WFL (50 μg/mL; D).