[WS4-6/ODP-031] Rheotaxis in Mycoplasma pneumoniae
Bacterial cell motility is controlled in response to environmental signals. A small parasitic bacterium, Mycoplasma pneumoniae, has an attachment organelle at a cell pole and moves over surfaces by its unique machinery. However there was no report so far about how M. pneumoniae control the moving direction on host cell surfaces. Considering the mucociliary clearance, a directional flow on the epithelial cells to the upper airways by ciliary beating, we setup a flow-controlled chamber that enable us to observe a lot of cell behaviors at once in a fluid flow. Here we found positive rheotactic behavior in the chamber; cells were re-oriented parallel to the flow direction and moved upstream in a fluid flow. The gliding speed decreased linearly with a slope of −0.07 μm s-1 in a range of flow rate at 0.5-4.0 mm s-1. At zero speed, the stall force was estimated to be 78 to 107 pN based on Stokes’ law, which is greater than the force of human ciliary beating reported in the previous study. Therefore this study provides the insight into how cells move under a flow from mucociliary clearance in host respiratory tract.