Biophysics

Dying to Survive

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Science  11 Jan 2013:
Vol. 339, Issue 6116, pp. 121
DOI: 10.1126/science.339.6116.121-b

Bacteria grown on surfaces often form dense communities, often with complex three-dimensional wrinkled structures, called biofilms. These are often problematic—for example, in industrial and medical settings—but can also be harnessed for uses such as waste remediation. Asally et al. showed that in Bacillus subtilis, wrinkling is caused by localized cell death that spatially focuses mechanical forces and may be a community-level stress response. Wilking et al., also working with B. subtilis, showed that the wrinkles make up the top of a network of channels that provide a system for enhanced transport of nutrients. As biofilms grow, nutrients are consumed by cells on the periphery, leaving bacteria in the center facing nutrient depletion. Such channels provide a conduit for nutrient flow and are most highly connected near the center of the biofilm. Flow through the channels was driven by spatial variation in evaporation and also by factors such as osmotic pressure gradients. Channels are internalized as the biofilm ages; however, the network remains permeable even in the late stages of biofilm growth, which suggests that the channels may be physiologically relevant throughout the biofilm life cycle.

Proc. Natl. Acad. Sci. U.S.A. 109, 18891; 10.1073.pnas.1216376110 (2012).

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