PT - JOURNAL ARTICLE AU - James Vesenka AU - James Havu AU - David Emerson TI - A model for sheath formation coupled to motility in <em>Leptothrix ochracea</em> AID - 10.1101/157073 DP - 2017 Jan 01 TA - bioRxiv PG - 157073 4099 - http://biorxiv.org/content/early/2017/06/28/157073.short 4100 - http://biorxiv.org/content/early/2017/06/28/157073.full AB - Optical and atomic force microscopy (AFM) of naturally occurring Leptothrix ochracea was used to study the fine structure of sheaths and cells. Morphology of young sheaths suggests the scaffold chains have strong self-adhesion. Evidence from un-encapsulated cells indicates fresh scaffold production through cell walls. Simple diffusion arguments are used to explain the morphology of the sheath structure. We propose a novel cell motility model based on previously published video data, our AFM images of naked cells, and simple flow calculations. The model indicates that motility results from differential shear forces resulting from extrusion of sheath material that passively pushes a filament of connected cells forward as the surrounding sheath material hardens behind the cell train.