Design and construction of 3D-printed devices to investigate active and passive bacterial dispersal on hydrated surfaces

Abstract

To disseminate in water-unsaturated environments, such as the soil, bacteria rely on the availability and structure of water films forming on biotic and abiotic surfaces, and, especially, along fungal mycelia. Dispersal along such “fungal highways” is driven both by mycelial physical properties and by interactions between bacteria and fungi. To understand the role of abiotic elements, we designed and 3D-printed two devices establishing stable liquid films that support bacteria dispersal in the absence of biotic interactions. The thickness of the liquid film determined the presence of hydraulic flow capable of carrying non-motile cells. In the absence of flow, only motile cells can disperse in the presence of an energy source. Non-motile cells could not disperse autonomously without flow, but dispersed when co-inoculated with motile cells. By teasing apart the physical and biological dimensions, these 3D-printed devices will stimulate further research on microbial dissemination in soil and other water-unsaturated environments.

Spatial scales of competition and a growth–motility trade-off interact to determine bacterial coexistence

“…However, our work showed that the glass fibre network is not an ideal abiotic substitute for the fungal network, partly because the liquid films formed around glass fibres are much thicker than those surrounding fungal hyphae (electronic supplementary material, figure S6). The thickness of liquid film determines whether cells can disperse solely actively by flagella-propelled swimming or also passively driven by hydraulic flow in the liquid film [69]. The hydraulic flow caused by inoculation may have flushed some KT2440 cells into the dispersal network, leading to a large variation in the competition outcome under the glass fibre treatment.…”

Spatial scales of competition and a growth-motility tradeoff interact to determine bacterial coexistence

“…However, our work showed that the glass fiber network is not an ideal abiotic substitute for the fungal network, partly because the liquid films formed around glass fibers are much thicker than those surrounding fungal hyphae (Supplementary Figure S6). The thickness of liquid film determines whether cells can dispersal solely actively by flagella-propelled swimming or also passively driven by hydraulic flow in the liquid film [69]. The hydraulic flow caused by inoculation may have flushed some KT2440 cells into the dispersal network, leading to a large variation in the competition outcome under the glass fiber treatment.…”