Self-organized canals enable long range directed material transport in bacterialcommunities*

Long-range material transport is essential to maintain the physiological functions of

multicellular organisms such as animals and plants. By contrast, material transport in

bacteria is often short-ranged and limited by diffusion. Here we report a unique form of

actively regulated long-range directed material transport in structured bacterial communities.

Using Pseudomonas aeruginosa colonies as a model system, we discover that a large-scale

and temporally evolving open channel system spontaneously develops in the colony via

shear-induced banding. Fluid flows in the open channels support high-speed (up to 450

µm/s) transport of cells and outer membrane vesicles over centimeters, and help to

eradicate colonies of a competing species Staphylococcus aureus. The open channels are

reminiscent of human-made canals for cargo transport, and the channel flows are driven by

interfacial tension mediated by cell-secreted biosurfactants. The spatial-temporal dynamics

of fluid flows in the open channels are qualitatively described by flow profile measurement

and mathematical modeling. Our findings demonstrate that mechanochemical coupling

between interfacial force and biosurfactant kinetics can coordinate large-scale material

transport in primitive life forms, suggesting a new principle to engineer self-organized

microbial communities.