Predatory bacterial swarm uses rippling motion to ...( Oct. 29 2008 Like something from ...)

Oct. 29, 2008

Like something from a horror movie, the swarm of bacteria ripples purposefully toward their prey, devours it and moves on.

Researchers at the University of Iowa are studying this behavior in Myxococcus xanthus (M. xanthus), a bacterium commonly found in soil, which preys on other bacteria.

Despite its deadly role in the bacterial world, M. xanthus is harmless to humans and might one day be used beneficially to destroy harmful bacteria on surfaces or in human infections, said John Kirby, Ph.D., associate professor of microbiology in the UI Roy J. and Lucille A. Carver College of Medicine.

"It may be that we can modify this predator-prey relationship or apply it to medically relevant situations," Kirby said. "It would be amazing if we could adapt its predatory ability to get rid of harmful bacteria that reside in places we don't want them, including in hospitals or on medical implants."

M. xanthus lives in a multi-cellular unit that can change its structure and behavior in response to changing availability of prey.

This adaptive ability to control movement in response to an environmental stimulus is called chemotaxis, and the research team coined the term predataxis to describe M. xanthus behavior in response to prey.

In earlier studies, Kirby and James Berleman, Ph.D., a postdoctoral fellow in Kirby's lab, showed that the presence of prey causes M. xanthus to form parallel rippling waves that move toward and through prey bacteria. Now, how the bacteria organize to form these traveling waves in response to the presence of prey is the subject of the UI team's latest study, which was published online Oct. 24 in Proceedings of the National Academy of Sciences (PNAS) Early Edition.

"When an M. xanthus aggregate is placed inside a colony of E. coli bacteria, the M. xanthus proceeds to eat the colony from the inside out and creates a rippling
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