Abstract
In nature, bacteria often live in surface-associated communities known as biofilms. Biofilm-forming bacteria typically deposit a layer of polysaccharide on the surfaces they inhabit; hence, polysaccharide is their immediate environment on many surfaces. In this study, we examined how the physical characteristics of polysaccharide substrates influence the behavior of the biofilm-forming bacterium Myxococcus xanthus. M. xanthus responds to the compression-induced deformation of polysaccharide substrates by preferentially spreading across the surface perpendicular to the axis of compression. Our results suggest that M. xanthus is not responding to the water that accumulates on the surface of the polysaccharide substrate after compression or to compression-induced changes in surface topography such as the formation of troughs. These directed surface movements do, however, consistently match the orientation of the long axes of aligned and tightly packed polysaccharide fibers in compressed substrates, as indicated by behavioral, birefringence and small angle X-ray scattering analyses. Therefore, we suggest that the directed movements are a response to the physical arrangement of the polymers in the substrate and refer to the directed movements as polymertropism. This behavior might be a common property of bacteria, as many biofilm-forming bacteria that are rod-shaped and motile on soft surfaces exhibit polymertropism.
Highlights
In nature, bacteria commonly live in surface-associated communities of cells known as biofilms
We have focused on the physical cues in polysaccharide substrates because biofilm-forming bacteria coat the surface to which they are attached with a matrix of polysaccharide[4,5,6] and polysaccharide is their immediate environment on many surfaces
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
Summary
Bacteria commonly live in surface-associated communities of cells known as biofilms. Based on the birefringence and small angle X-ray scattering patterns of compressed polysaccharide substrates, and the results of surface spreading assays, we conclude that the directed group movements and expansion on polysaccharide substrates matches the orientation of the long axes of aligned and tightly packed polysaccharide fibers in the substrates. This behavior, which we refer to as polymertropism, might be a common property of bacteria, as many biofilm-forming bacteria that are rod-shaped and motile on soft surfaces are positive for polymertropism. A model for the mechanism of polymertropism, and the potential roles of polymertropism in the behavior and organization of biofilm-forming bacteria are discussed
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call