Amazing stuff!
"Bacterial cells in solutions of polymers such as mucus grow into long cable-like structures that buckle and twist on each other, forming a “living gel” made of intertwined cells. This behaviour is very different from what happens in polymer-free liquids, and researchers at the California Institute of Technology (Caltech) and Princeton University, both in the US, say that understanding it could lead to new treatments for bacterial infections in patients with cystic fibrosis. It could also help scientists understand how cells organize themselves into polymer-secreting conglomerations of bacteria called biofilms that can foul medical and industrial equipment. ..."
From the abstract:
"Many bacteria live in polymeric fluids, such as mucus, environmental polysaccharides, and extracellular polymers in biofilms. However, laboratory studies typically focus on cells in polymer-free fluids.
Here, we show that interactions with polymers shape a fundamental feature of bacterial life—how they proliferate in space in multicellular colonies. Using experiments, we find that when polymer is sufficiently concentrated, cells generically and reversibly form large serpentine “cables” as they proliferate. By combining experiments with biophysical theory and simulations, we demonstrate that this distinctive form of colony morphogenesis arises from an interplay between polymer-induced entropic attraction between neighboring cells and their hindered ability to diffusely separate from each other in a viscous polymer solution. Our work thus reveals a pivotal role of polymers in sculpting proliferating bacterial colonies, with implications for how they interact with hosts and with the natural environment, and uncovers quantitative principles governing colony morphogenesis in such complex environments."
A 3D rendering captured by a confocal microscope shows the development of serpentine "cables" as non-motile E. coli bacterial cells proliferate in a polymeric solution.
Fig. 3. Polymer-induced entropic attraction between cells is required for cable formation.
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