A study by Princeton University scientists has shown that bacteria actively move around their environments to form social organizations. The researchers placed bacteria in minute mazes and found that they sought each other out using chemical signals.

Biologists have become increasingly aware of social interactions among bacteria, but previously believed that clusters formed only when bacteria randomly landed somewhere, then multiplied into dense populations. The discovery that they actively move into gatherings underscores the importance of bacterial interactions and could eventually lead to new drugs that disrupt the congregating behavior of harmful germs, said Jeffry Stock, a professor of molecular biology and coauthor of the paper.

"It makes sense, but it's surprising that it's as pervasive as it now seems to be," said Stock.

The researchers observed the gathering behavior in E. coli as well as in V. harveyi, a marine bacteria that glows when it achieves a high-density population. They found that when placed in mazes the bacteria congregated in small rooms and dead-end pathways. Once clustered, the V. harveyi turned on the genes that make them glow.

Biologists had previously believed that bacteria's ability to move and follow chemical signals -- a process called chemotaxis -- was primarily a means of dispersing and seeking food. The new study, published in the July 11 issue of Science, shows that chemotaxis may also be important for facilitating cooperative behavior.

The work was collaboration between Stock's lab in biology and that of Robert Austin, a professor of physics. Emil Yuzbashyan, a graduate student in Austin's lab noticed unusual clumping when he put E. coli into microscopically small mazes made of silicone. Biologists in Stock's lab supplied mutant strains of bacteria that lacked genes necessary for sensing chemical signa
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Contact: Steven Schultz
sschultz@princeton.edu
609-258-5729
Princeton University
28-Jul-2003