Friday, October 21, 2005

Talking bacteria


Consider the meadow of grazing organisms in the photograph above. These are bacteria, Pseudomonas aeruginosa, a human pathogen that is a particular problem in the lungs of cystic fibrosis patients. How big? Well, a thousand of the "meadows" shown in the photo would fit on the period at the end of this sentence.

Certainly, bacteria are not as sophisticated as cows or sheep, but don't sell them short. Not least among their talents is their ability to communicate with friends. Their "speech" is molecular. For example, when the density of emitted "quorum sensing" molecules reaches a certain density, whole sets of genes are activated within a bacterial population, including genes for infecting plants, animals and humans.

But many "speech" molecules are poorly water soluble, which limits the ability of bacteria to talk to one another in aqueous environments. "Speech" molecules can also be broken down and made unintelligible by rival bacteria. To keep their chat intact, P. aeruginosa wrap their messages in protective, water-transportable membranes.

Imagine, then, if you will, the bacteria in the photograph with little cartoon bubbles of speech over their "heads." "Are you here?" "Friend or enemy?" "Time for attack!" "Let's go."

This is why I read Science and Nature every week; there is no end of wonderful stuff to be learned about the world. The deciphering of P. aeruginosa speech is described in the September 15th issue of Nature, by Lauren Mashburn and Marvin Whiteley of the University of Oklahoma. Learning how bacteria talk among themselves -- coordinating their attacks, for example -- is an advantage if we want to beat them at their own game.

And while I'm at it, here is a stanza from a poem on one-celled creatures by the inimitable Pattiann Rogers in the September issue of POETRY:

Far too ancient for scripture, each
one bears in its one cell one text --
the first whit of alpha, the first
jot of bearing, beneath the riling
sun the first nourishing of self.