Are sacrificial bacteria altruistic or just unlucky?

April 15, 2008

An investigation of the genes that govern spore formation in the bacteria B. subtilis shows that chance plays a significant role in determining which of the microbes sacrifice themselves for the colony and which go on to form spores.

B. subtilis, a common soil bacteria, is a well-known survivor. When running short of food, it can alternatively band together in colonies or encase itself in a tough, protective spore to wait for better times. In fact, B. subtilis is so good at making spores that it's often used as a model organism by biologists who study bacterial spore formation.

"It's too early to say whether B. subtilis is truly altruistic," said co-author Oleg Igoshin, assistant professor of bioengineering at Rice University. "What is clear from this is that not all bacteria are going to look and act the same, and that's something that can be overlooked when people either study or attempt to control bacteria with population-wide approaches."

For example, Igoshin said doctors and food safety engineers might need to amend general approaches aimed at controlling bacteria with more targeted methods that also account for the uncharacteristic individual.

The new results appear in the April 15 issue of Molecular Systems Biology. The experimental work, which was done by Jan-Willem Veening, currently at Newcastle University, and by other members of Oscar Kuipers' research group at the University of Groningen in the Netherlands, focused on the B. subtilis genes that regulate both spore formation and the production cycles of two proteins -- subtilisin and bacillopeptidase. These two proteins help break apart dead cells and convert them into food. They are produced and released into the surrounding environment by B. subtilis cells that are running low on food.

From previous studies, scientists know there is some overlap between genes that control the production of the two proteins and those that control spore formation.

"Only a portion of the bacteria in a colony will form spores and only portion of the bacteria produce subtilisin, and we were interested in probing the genetic basis for this," Igoshin said. "How is it decided which cells become spores and which don't?"

Igoshin, a computational biologist, used computer simulations to help decipher and interpret the team's experimental results. He said the team found that fewer than 30 percent of individuals in a colony produce large quantities of the food-converting proteins. Even though the proteins benefit all members of the colony and help some cells to become spores, the cells that produce the proteins in bulk do not form spores themselves.

"There's a feedback loop, so that cells that start producing the proteins early get a reinforced signal to keep making them," Igoshin said. "We found that it's probabilistic events -- chance, if you will -- that dictates who is early and who is late. The early ones start working for the benefit of everyone while the later ones save valuable resources to ensure successful completion of sporulation program. Many cells will end up committing to sporulation before they had a chance to contribute to protease production"

Igoshin said a key piece of evidence confirming modeling predictions came in experiments that tracked genetically identical sister cells, some of which became protein producers and some of which didn't.

Source: Rice University

Explore further: Researchers solve mystery of how AkT 'moves' from cytosol to cell membrane

Related Stories

Why bacteria could be the answer to a future without oil

July 30, 2015

Chemicals are all around us. They are crucial in all manner of industries, from agriculture to food to cosmetics. Most people give little thought to how these chemicals are made – and certainly very few would consider the ...

Researchers build bacteria's photosynthetic engine

July 29, 2015

Nearly all life on Earth depends on photosynthesis, the conversion of light energy into chemical energy. Oxygen-producing plants and cyanobacteria perfected this process 2.7 billion years ago. But the first photosynthetic ...

Researchers design first artificial ribosome

July 29, 2015

Researchers at the University of Illinois at Chicago and Northwestern University have engineered a tethered ribosome that works nearly as well as the authentic cellular component, or organelle, that produces all the proteins ...

Plant light sensors came from ancient algae

July 28, 2015

The light-sensing molecules that tell plants whether to germinate, when to flower and which direction to grow were inherited millions of years ago from ancient algae, finds a new study from Duke University.

Recommended for you

How bees naturally vaccinate their babies

July 31, 2015

When it comes to vaccinating their babies, bees don't have a choice—they naturally immunize their offspring against specific diseases found in their environments. And now for the first time, scientists have discovered how ...

Image: Hubble sees a dying star's final moments

July 31, 2015

A dying star's final moments are captured in this image from the NASA/ESA Hubble Space Telescope. The death throes of this star may only last mere moments on a cosmological timescale, but this star's demise is still quite ...

Exoplanets 20/20: Looking back to the future

July 31, 2015

Geoff Marcy remembers the hair standing up on the back of his neck. Paul Butler remembers being dead tired. The two men had just made history: the first confirmation of a planet orbiting another star.

Earth flyby of 'space peanut' captured in new video

July 31, 2015

NASA scientists have used two giant, Earth-based radio telescopes to bounce radar signals off a passing asteroid and produce images of the peanut-shaped body as it approached close to Earth this past weekend.

Binary star system precisely timed with pulsar's gamma-rays

July 31, 2015

Pulsars are rapidly rotating compact remnants born in the explosions of massive stars. They can be observed through their lighthouse-like beams of radio waves and gamma-rays. Scientists at the Max Planck Institute for Gravitational ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.