Sibling Rivalry

Thursday, January 8, 2009

Two sibling colonies of Paenibacillus dendritiformis fight along their border (the space down the middle). Each colony exudes growth inhibitors that only keep each other at bay at high concentrations. Adapted from Be'er et. al.

Here’s what happens when you put some of the world’s smartest and most creative physicists in the same mental space with some of the world’s greatest bacteriologists:

Border maintenance among warring colonies of bacteria is explained by applying a little math.

That, my friends, is science at work.

Physicists Harry Swinney and Avraham Be’er, collaborating with biologist Shelley Payne and several others, recently found that two sibling colonies of bacteria inhibit each others' growth by secreting antibacterial compounds. Seems intuitive.

A little less obvious is that somehow the colonies survive in a sea of their own growth inhibitors.

The scientists discovered that’s because the compounds being released by the two colonies  inhibit growth only when their defenses have combined to reach high concentrations along their leading edges, much like increased missile defenses might keep warring parties at bay along a battlefront.

Henry Fountain reported on the phenomenon in his New York Times Observatory column here.

The article was published in the early edition of the Proceedings of the National Academy of Sciences, and co-authors include: Hepeng Zhang, E.L. Florin and Eshel Ben-Jacob (Tel Aviv University).