Figure 1.

Experimental evidence for bacterial thread-like biofilms (streamers) in curved microchannels. (a) Schematic of the microfluidic device in which bacterial solutions, containing cells and nutrients, flow through the channel for several hours. The width of the channel is 200 μm and the typical height is about 100 μm. (b) Bacterial streamers developed in the channels after 12 h at constant flow rate (corresponding to an average speed of 0.75 μL/min) for two different experiments. The flow direction is from left to right. Bacteria are fluorescently labeled, and images of the middle plane of the channel are taken with a confocal microscope. Scale bars, 100 μm. (c) Three-dimensional reconstruction from z-scan confocal images and cross-sectional views are shown (red box in (b) depicts observed location). (d) Three-dimensional reconstruction from z-scan confocal images and cross-sectional views are shown (blue box in (b) depicts observed location). (e) The helicoidal bacterial threads (streamers) formed in the inner wall of circular channels. Images of (a)–(d) are cited from Rusconi et al. [12]. Image of (e) is cited from Rodríguez Espeso 2013. TB is tryptone broth. The microfluidic channels were prepared from polydimethylsiloxane (PDMS, Sylgard 184 silicone elastomer kit, Dow Corning) following conventional soft-lithography techniques.