Motility of bacteria in microfluidic structures

Traditionally bacteria are cultivated on the surface of agar, an environment that is experimentally convenient, but it does not resemble the diverse micro-geometries of their natural habitat, such as abiotic (e.g., soil) and biotic (e.g., plant and other organisms) surfaces. In this work, microstructured environments were manufactured from a biocompatible polymer, polydimethylsiloxane, to test the motility behaviour of bacteria moving into complex, channel-like, closed geometries with different shapes and dimensions. The motile bacteria were imaged by light microscopy and observed in replicate trials. It was found that bacteria were capable of swimming through even narrow microchannels and that their swimming paths, velocity and modes were influenced by a combined effect of channel width and its complexity. These results show that the structured microfluidic environment can be used as a simple means to observe and quantify the movement and navigation behaviour of bacteria through geometrically heterogeneous environments.