Jekyll and Hyde bacteria aids or kills, depending on chance

Jul 05, 2012
Jekyll and Hyde bacteria live and thrive in the guts of worms. Credit: Photo courtesy of Alex Martin.

Living in the guts of worms are seemingly innocuous bacteria that contribute to their survival. With a flip of a switch, however, these same bacteria transform from harmless microbes into deadly insecticides.

In the current issue of Science, Michigan State University researchers led a study that revealed how a bacteria flips a DNA switch to go from an upstanding community member in the gut microbiome to deadly killer in insect blood.

Todd Ciche, assistant professor of microbiology and , has seen variants like this emerge sometimes by chance resulting in drastically different properties, such as being lethal to the host or existing in a state of mutual harmony. Even though human guts are more complex and these interactions are harder to detect, the revelation certainly offers new insight that could lead to , he said.

"Animal guts are similar to ours, in that they are both teeming with microbes," said Ciche, who worked with researchers from Harvard Medical School. "These bacteria and other microorganisms are different inside their hosts than isolated in a lab, and we're only beginning to learn how these alliances with are established, how they function and how they evolve."

The bacteria in question (Photorhabdus luminescens) are bioluminescent insect pathogens. In their mutualistic state, they reside in the intestines of worms, growing slowly and performing other functions that aid 's survival, even contributing to reproduction.

As the nematodes grow, the bacteria reveal their dark side. They flip a DNA switch and arm themselves by growing rapidly and producing deadly toxins. When the worms begin infesting insects, they release their bacterial .

"It's like teaming up with the plague," Ciche said.

The question remains: What causes this dramatic transformation?

"If we can figure out why the DNA turns on and off to cause the switch between Jekyll and Hyde, we can better understand how bacteria enter stages of dormancy and antibiotic tolerance – processes critical to treating chronic infections," Ciche said.

Explore further: Researchers film protein quake for the first time

More information: "A Single Promoter Inversion Switches Photorhabdus Between Pathogenic and Mutualistic States," by V.S. Somvanshi et al., Science, 2012.

Related Stories

Making microscopic worms into a more deadly insecticide

Jan 15, 2010

Microscopic nematode worms can be a potent organic insecticide, killing crop-raiding bugs without harming plants or beneficial insects and without environmental side effects of chemical. The problem is that ...

Cancer-causing gut bacteria exposed

Sep 22, 2008

Normal gut bacteria are thought to be involved in colon cancer but the exact mechanisms have remained unknown. Now, scientists from the USA have discovered that a molecule produced by a common gut bacterium activates signalling ...

Recommended for you

Researchers film protein quake for the first time

11 hours ago

One of nature's mysteries is how plants survive impact by the huge amounts of energy contained in the sun's rays, while using this energy for photosynthesis. The hypothesis is that the light-absorbing proteins ...

Deploying exosomes to win a battle of the sexes

Aug 25, 2014

There are many biological tools that help animals ensure reproductive success. A new study in The Journal of Cell Biology provides further detail into how one such mechanism enables male fruit flies to imp ...

User comments : 0