Understanding Microbial Polarity

The Science

Microbes are not just “bags of salt water” in which everything floats freely and is evenly distributed inside a spherical cell. Instead, microbes establish and maintain the unequal distribution of their internal components, i.e., they have “polarity.” Polarity enables a microbe to move in the direction of a nutrient or away from a toxin, divide unequally into daughter cells that can display different behaviors (one can swim off looking for a new place to live and eat and the other may stay behind), or from structures that push the cell in one direction or another. A Stanford University research team is studying polarity in a microbe, Caulobacter crescentus, whose DNA was sequenced with Biological and Environmental Research support and that can remediate heavy metals in aquatic environments. A review article in the December 6, 2002, issue of Science, surveys the establishment of polarity in this and other microbes. This is a key step towards understanding the reality of complex microbial biology and the eventual use of microbes to address DOE needs in energy and the environment.


Bacteria are often highly polarized, exhibiting specialized structures at or near the ends of the cell. Moving toward food, adapting to environmental extremes, and, in many cases, entering and exploiting a eukaryotic host – these activities often involve processes that take place at or near the poles of the cell. Among such structures are actin-organizing centers, which mediate the movement of certain pathogenic bacteria within the cytoplasm of an animal host cell; organized arrays of membrane receptors, which govern chemosensory behavior in swimming bacteria; and asymmetrically positioned septa, which generate specialized progeny in differentiating bacteria. This polarization is orchestrated by complex and dynamic changes in the subcellular localization of signal transduction and cytoskeleton proteins as well as of specific regions of the chromosome. Recent work has provided information on how dynamic subcellular localization occurs and how it is exploited by the bacterial cell. “New” poles generated at the cell division plane differ from old poles from the previous round of cell division.

BER Program Manager

Ramana Madupu

U.S. Department of Energy, Biological and Environmental Research (SC-33)
Biological Systems Science Division
[email protected]


Shapiro, L., H. H. McAdams, and R. Losick. 2002. “Generating and Exploiting Polarity in Bacteria,” Science 298. DOI:10.1126/science.1072163.