Cells can adapt their motion to the environment by sensing the mechanical and chemical cues. We discovered a new mode of mechanosensing in M. xanthus bacteria where when the polysaccharide fibers in agar are forced into alignment and to pack tightly via compression, groups of M. xanthus cells change their movements to match the orientation of the long axes of the fibers. We termed this behavior polymertropism. This behavior is shared among many rod, motile bacteria.  Polymertropism could play a role in biofilm formation via slime trail following, where the aligned polysaccharide fibers secreted by one cell could provide a trail for another cell to follow.

The social amoeba Dictyostelium discoideum performs chemotaxis under starvation conditions, aggregating towards clusters of cells following waves of the signaling molecule cAMP. We developed a biophysical model to integrate the signal relay network with the chemotaxis network to explain the perfect adaptation and timescale matching observed in Dictyostelium chemotaxis.