Fig. 2: Spatial and time dependent bacterial distribution in a confined stagnant environment.
a Illustration of bacterial spatial distribution in the microfluidic channel. Motile bacteria, in green, experience a trapping effect at channel walls due to the boundary layer effect, while non-motile bacteria, in yellow, slowly sediment at the bottom of the channel. We reported as Lz the characteristic depth of the layer where cell experience the trapping effect, and we distinguished the different diffusivity coefficient near the wall and in the middle of the channel. b Spatial distribution of bacterial density at inoculum and after 2 h in stagnant conditions in a microfluidic channel. The x-axis represents bacterial density in number per square millimetre, while the height is measured relative to reference points in the microfluidic channel. The maximum height (400 μm) corresponds to the top layer z5, and 0 μm represents the bottom layer z1. Motile bacteria are depicted in green, appearing light at time 0 and dark after 2 h. Non-motile bacteria on the surface are shown in yellow, appearing light at time 0 and dark after 2 h. c Temporal evolution of bacterial density over 0 to 2 h corresponding to the layers visualized in graph A. Accumulation of bacteria is observed at the surfaces of the layers, while a depletion is noticeable in the middle layers of the channel.
