Wednesday, September 26, 2007

The World Of Germs Becomes Deadlier In Space

Salmonellae are primarily intestinal parasites of man and animals, both domestic and wild. They are frequently found in sewage, river and other waters and soil. They may survive for weeks in water and for years in soil. Image Credit: - 11/3/2006

The World Of Germs Becomes Deadlier In Space

That’s right, it has been discovered that germs become stronger and deadlier when they are not confined to the limitations that gravity brings to the growth and development of these microbes.

This discovery was part of a package of experiments performed on a shuttle flight that took off and landed about one year ago. On board the Shuttle, Salmonellae was carried along on the flight while a control sample from the same batch was kept here on this Oblate Spheroid at the same temperature conditions as the ones on the flight.

After the mission, study mice were fed the control bacteria and the results came back as follows.

Excerpts from a story published in U.S. News & World Report by Associated Press about a study that appeared in this Tuesday’s edition of Proceedings of the National Academy of Sciences –

Germs Taken to Space Come Back Deadlier
By RANDOLPH E. SCHMID - AP Science Writer - Sep 24, 9:03 PM EDT

It sounds like the plot for a scary B-movie: Germs go into space on a rocket and come back stronger and deadlier than ever. Except, it really happened.

The germ: Salmonella, best known as a culprit of food poisoning.

The trip: Space Shuttle STS-115, September 2006.

The reason: Scientists wanted to see how space travel affects germs, so they took some along - carefully wrapped - for the ride.

The result: Mice fed the space germs were three times more likely to get sick and died quicker than others fed identical germs that had remained behind on Earth.

"Wherever humans go, microbes go, you can't sterilize humans. Wherever we go, under the oceans or orbiting the earth, the microbes go with us, and it's important that we understand ... how they're going to change," explained Cheryl Nickerson, an associate professor at the Center for Infectious Diseases and Vaccinology at Arizona State University.

Nickerson added, in a telephone interview, that learning more about changes in germs has the potential to lead to novel new countermeasures for infectious disease.
After 25 days, 40 percent of the mice given the Earth-bound salmonella were still alive, compared with just 10 percent of those dosed with the germs from space. And the researchers found it took about one-third as much of the space germs to kill half the mice, compared with the germs that had been on Earth.

The researchers found 167 genes had changed in the salmonella that went to space.

Salmonella pullorum is a host-adapted pathogen of poultry previously thought to be nonmotile and nonflagellated. Motility can be induced in this organism under special medium conditions and this motility was observed in 39 of 44 S.pullorum isolates tested. Image Credit: Geocities


"That's the 64 million dollar question," Nickerson said. "We do not know with 100 percent certainty what the mechanism is of space flight that's inducing these changes."

However, they think it's a force called fluid shear.

"Being cultured in microgravity means the force of the liquid passing over the cells is low." The cells "are responding not to microgravity, but indirectly to microgravity in the low fluid shear effects."
"These bugs can sense where they are by changes in their environment. The minute they sense a different environment, they change their genetic machinery so they can survive," she said.

The research was supported by the National Aeronautics and Space Administration, Louisiana Board of Regents, Arizona Proteomics Consortium, National Institute of Environmental Health Sciences, Southwest Environmental Health Sciences Center, National Institutes of Health and the University of Arizona.
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