March 2006 Archives

Ben Jacob's Fractal Bacteria

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Eshel_ben_Jacob_bacteria_vortices_300pixels.jpg Images by Eshel Ben Jacob

The once-controversial idea that bacteria communicate and cooperate—both within and between species—has become widely accepted thanks to the work of molecular biologists such as Princeton University’s Bonnie Bassler.

Tel Aviv University physicist Eshel Ben Jacob studies one visually stunning result of this phenomenon: the growth patterns bacteria form in response to laboratory-imposes stresses. Ben Jacob subjects his petri-dish colonies to such challenges as borderline starvation and infusions of noxious chemicals, just the kinds of threats that microorganisms must survive in nature. The colors and shading of his images represent artistic license, but the underlying images are of actual colonies of tens of billions of organisms.

In response to Septrin antibiotic, for example, colonies of Paenibacillus dedritiformis bacteria secrete “come-hither” signals that cause their members to drawer closer together and form large vortices. This increases the colony’s ability to dilute the antibiotic with the lubricating fluid secreted by individual microbes. By contrast, when faced with a sparcity of food, the colony reorganizes into narrow, straight branches that maximize contact with the limited nutrients in its environment.

Here’s the link to Ben Jacob’s gallery of images and an introduction to his ideas on the foundation of cognition in bacteria.