Figure 1.

Microscopy observations of the inoculated medium adsorbed on glass wool. The calculated thickness [see Additional file 3] was confirmed by confocal microscopic observation of several pieces of GW loaded with a ratio of 5 mL/g GW (A, C) or 2.5 mL/g GW (B) of LB containing PAO1. In any case, we observed a minimal thickness of ≈ 15 μm even when several fibers were intertwined (C). The black line on schematic representation indicates the fibers on the focal plane.